Heat-sealing cartons



July 13, 1965 G. G. RUMBERGER 3,194,474

HEAT-SEALING cARToNs 93] Ui i F|GURE 3 i l HNI July 13, 1955 G. G.RUMBERGER 3,194,474

HEATf-SEALING CARTONS Filed Aug. 25, 1961 5 Sheets-Sheet 5 //6Z MIMIlNvENToR FlGuRl-I 26 TTORNEY United States Patent C) 3,194,474HEAT-SEALNG CARTONS George G. Bamberger, Portage Township, KalamazooCounty, Mich., assigner to KVP Sutherland Paper Company, Kalamazoo,Mich., a corporation of Delaware Filed Aug. 23, 1961, Ser. No. 133,43939 Claims. (Cl. 229-37) The present invention relates to carton blanksand cartons, and is more particularly concerned with carton blanks inwhich the adhesive for sealing of the carton erected from such blanks isindigenous to the material of :construction of the 4carto-n blanks, witherected and sealed cartons formed from such blanks, and with a novelmethod of forming such carton blanks and sealed car tons. yBecause theadhesive in certain requisite amounts is indigenous to the particularmaterial of construction of the carton blanks of the invention andcartons formed thereform in preselected heat-sealing areas where such isrequired, eg., in the closure flaps, there is no need to provideadhesive extraneously. Because of certain means provided in the saidheat-sealing areas, the adhesive is both activated and provided lin.pl-ace in :the preselected carton areas, in which a seal is desired,upon the application of adhesive-activating conditions. The combinationof these several elements allows results which are unprecedented in thecarton ield.

The carton blanks and cartons of the present invention are constructedof laminated sheet material in which the laminant -is a thermoplasticlaminant adhesive which lis present in the said sheet material in atleast a certain necessary minimal quantity per ream, or in at least acertain necessary minimal thickness. The base plies of the saidlaminated sheet material also have certain requisite characteristics.

By the provision of the said laminated sheet material having thecer-tain requisite base sheet and laminant characteristics and byproviding scored carton blanks and cartons thereof, which areadditionally provided 'with (a) openings, e.g., slits, cuts, or foramen,from the outer surface `of at least one ply of the laminated sheetmaterial into the intercalated thermoplastic laminant adhesive inheat-sealing areas where the surface of an end, side, front, or otherclosure flap or carton `faces lies or will -lie in opposed facingrelationship with the surface of `another Hap or carton face to which itis t-o be secured, or alternatively with (b) perforations extendingentirely through such a carton member, e.g., closure flap, from face toface and through all plies thereof, especially where both surfaces ofsuch carton member, eg., closure flap, lie or will lie in opposed facingrelationship with other carton surfaces, unprecedented carton seals areattained upon activation of the thermoplastic adhesive laminantindigenous to Ithe carton construction in 'the said heat-sealing areasthereof to cause extrusion of the said adhesive through the said plyopenings, and setting of the adhesive by allowing the same to congeal,thereby providing bodies vof solidified adhesive integrally bonding thevarious surfaces and plies of the carton construction together in thesaid heat-sealing areas. The carton blanks, cartons, and method offorming blanks and sealed cartons according to the present invention areofparticularinterest with relation to the provision of leakproof andhermetically sealed cartons or carton-like containers and the hermeticclosure thereof, all of which is accomplished by extrusion of thethermosplastic lamin-ant adhesive in the molten or semi-molten statethrough the ply openings provided in said carton heat-sealing areas, andfrom cut edges also provided in the carton construction. In onepreferred embodiment of lthe invention, an intermediate closure llap ofthe carton is recessed at its edges so that an outer ilap of the cartonoverlies the intermediate flap along its edges, so as to provide an areaof opposed facing relationship between an `outer ap' and an inner flapor aps in the area of overhang of said intermediate ap by said outerflap, all of said flaps carrying thermoplastic laminant adhesiveintercalated between the plies ofy their base sheet materials, whichadhesive is provided and activated in pla-ce at least in the said `areaof overhang through cut edges and preferably also through openingsprovided in the plies of said aps in the Iarea of overhang, Ias well asthrough additional openings in other heat-sealing areas of the flapsthereby providing carton closures and seals which are unprecedented asto their strength and, if desired, proofness, and therefore ofparticularly interest for hermetic sealing. All these results yareaccomplished by the particular combination of method and means for theprovision, activation, extrusion, and'setting of the `thermoplasticlaminant adhesive of the sheet material of the carton construction inthe preselected carton heat-sealing areas, which thermoplastic adhesivelamvinant is moreover substantially `and usually completely absent fromthe exterior exposed faces of the sealed carton.

Numerous carton blanks and cartons have already been proposed andadopted in practice which are provided on at least one end or elsewherewith closure flaps or members, adapted to be overlapped with othercarton members or folded over and in any event adhesively secured. Sideseams, side overlaps, `front closures, top and vbottom closures, and thelike, are thereby provided. `In many instances, the carton blank orcarton is provided with similar ilaps at bothends. In such cartons, forexample, at one or both ends, a carton closure is Yusually formed byadhesively securing laps which lie with the `surface of one flap uponthe surface of another ap, with certain of the flaps presenting free orcut edge surfacesvalong opposite edges of the closure. The contiguoussurfaces may be either horizontal, as with top and bottom end closureflaps, or vertical, las with side closures or seams, front closureflaps, or the like. This is the case whether the shape of the carton isconventionally square or rectangular, or lround, oval, triangular,pentagonal, hexagonal, or otherwise polygonal, in its cross-sectionalconfiguration, or any of numerous additional shapes in ywhich suchtypecartons are already known lor can be made. Such types of cart-onsmay be sealed by conventional gluing in a preselected sealing area, andin some cases may be provided with hot Imelt or other adhesives on the=inner surfaces of outer or intermediate aps, for sealing of the cartonupon the application of heat or heat and pressure thereto. However,these methods of sealing have not been successful in eliminating theedgewicking of vapors and liquids and the consider-able transfer through thecarton ywhich results in this manner remains an unsolved packagingproblem. -Mor`eover, the application of hot metal adhesives to preformedcarton blanks'cut from "base sheets laminated together withthermoplastic adhesives has been impossible due to delamination of thesheet materials during the application ofthe hot melt adhesive, orduring its reactivation onpackagin'g machinery, and thus the use of animportant class of packaging materials, viz., `laminated Sheetmaterials, in jheat sealing car-tons lhas been precluded.

ll i by wicking or otherwise. While there can be no question about theinitial proofness or seal of cartons which are wax-dipped, this isindeed an untidy and uneconomic operation and not one which canreadilybe accomplishedV coated area but especially along free edges of flaps,and.

rupture of the coating material along a surface or edge of the cart-onadjoining any area of overlap of one flap by another flap also tends torupture coating material collected therein due to stresses on theexposed coating which are conveyed from the exterior via the integralmass of coating material. Moreover, wax dipped or coated cartons leavemuch to be desired by way of their appearance and, in handling,considerable amounts of coating provided by a dipping, painting, orspraying operation frequently chip off and cause displeasure,discomfort, annoyance and an unsightly appearance when coming intocontact with the contained product or with hands, cloth-V ing, orpersonal effects of the consumer. In addition, dipped cartons have atendency to block together during hot Weather or upon temperatureincreases generally, causing loss-of protectiveness when the packagesare separated for distribution, so that dipping, spraying, or paintingis in fact avoided whenever possible, as `by innerwrapping of theproduct, overwrapping of the carton, or the like, which approaches inturn also involve additional steps or operations and leave much to bedesired.

It has moreover already been proposed to provide heatsealing sheetmaterials by laminating a relatively porous tissue sheet to anadhesive-impermeable sheet in a manner such that the laminating adhesivedifferentially migrates in various Ways through the porous tissue on theapplica- Y tion of heat, as in the United States patents of Farrell etal., 2,430,459, 2,446,414, and 2,474,619, Graebner et al. 2,415,387, orIreton 2,714,952. Although this approach has been successful inproviding Aheat-sealing bags,

' carton-overwraps and labels, it has been found lacking in a number ofimportant respects when attempted to be adapted to combinations ofheavier sheets, especially heavier non-porous sheets or combinations inwhich both sheets are porous or have equal migration rates for thelaminating adhesive, and particularly unadaptable to cartons, especiallyscored cartons of the type with which the present invention isconcerned, and most of all unadaptable to the production of cartons ofthe leakproof orl hermetically sealed type. The present applicant isfully cognizant of all of these prior art procedures, practices andproposals, as well as their shortcomings, having been integrallyassociated with the packaging industry, and Vespecially the cartonindustry, for a period of over twenty years.

Thus, despite the fact that it has long been recognized that 'it wouldbe highly desirable to have available cartons which could be rapidly andeffectively sealed, especially on rapidly-moving carton erecting andfilling equipment as ordinarily employed in the packaging industry,which would be equally adaptable to both leakproof and non-leakproofclosures, and especially adaptable to proofed or hermetic sealing, whichwould not be subject to the disadvantages attendant upon previousprocedures involving innerwrapping, overwrapping, dipping, spraying,painting or the like, al1 efforts up to the present time have fallenshort of this objective.

It is therefore Van object of the present invention to provide cartonswhich carry within the materials of their construction as an indigenouspart thereof their own Vsealing adhesive, and which are not subject tothe disadvantages hereinbefore mentioned. Another object lof theinvention is to provide cartons which are sealable by heat or heat andpressure or `like adhesive-activating conditions to provide a moresatisfactory seal, of the various carton closures thereof, thanpreviously attained or attainable by any known method or possible in anypreviously known carton of the same or similar type. Another cbject isthe provision of such a carton ink which the edges Vof both the outerand the intermediate flap which underlies the outer flap may optionallybe'completely and conveniently sealed. An additional object is theprovision of heat-sealing cartons which'may be sealed by the applicationof heat or heat and pressure and Vwhich do not bow because of theapplication of such conditions as is commonly experienced with such typesealing cartons.

A further object of t-he invention is to provide such cartons which sealreadily andV effectively upon the application of heat or heat andpressure due to the fact that, especially when heat alone is employed,:onlyV one layer of carton thickness must be Vpenetrated to effectuatethe seal. A still further object is the provision of carton blanks fromwhich such cartons are. produced, and still an additional object is theprovision ofsuch carton blanks and cartons formed therefrom which arecharacterized by the presence of an inner flap, an intermediate flap,and an outer flap, which flaps are adapted to be folded in sequence toprovide a plural layered closure in which the flaps lie with the surfaceof one flap upon thersurface of another, and in which at least one ofsaid intermediate and outer flaps is provided, in a ply thereofconstituting one of the` surfaces Vof said intermediate and outer flapswhich corne into opposed facing relationshipV upon folding of the tiapsand closing of the carton, with openings from the outer surface thereofto the intercalated laminant layer thereof, whereby upon erecting acarton therefrom, closing .of the flaps, and applying thermoplasticlaminant adhesive-activating conditions to said ap provided with saidopenings the thermoplastic adhesive laminant is caused to extrude fromthe intercalated laminant layer thereof through said openings, andwhereby upon cooling or congealing of Vthe thus-extruded laminant an'effective seal of said outer flap to said intermediate ap is providedin the area Vof their opposed facing relationship by means of bodies ofsolidified thermoplastic laminant adhesive extending from theintercalated laminant layer of at least the one flap through theopenings provided in the ply of that flap to at least the surface of theother flap. When the opposing plies of the several aps are Vbothprovided with such openings, the solidified bodies of the adhesive willextend from the outer ply of the one flap through the openingsto theouter ply of the other flap. Additional objects involve the provision ofcaiton blanks and cartons in which openings into the intercalated layerof thermoplastic laminant adhesive are provided in more than konesurface `of the same` flap, or various plies constituting opposing ornon-opposing surfaces of different iaps, Vand still an additional objectis the provision of such carton blanks and cartons formed therefrom asareV also characterized by an area of overlap between the outer andintermediate carton flap closure members and in which theadhesive-'necessary for the sealing of such cartons'is indigenoustosaidaps and adapted to be disposed in the said area of overlap of theintermediate liap by the outer flap and activated upon the applicationof `adhesive-activating conditions. A further object is the provision ofa novel method of forming such carton blanks and sealed cartons asaforesaid. Other objects of the invention will become apparent to oneskilled in the art and still other objects will become apparenthereinafter. i

I have now found that I can overcome many of the previous disadvantagesof'heat-sealing and leakproof cartons by not only constructing myVcartons from laminated sheet materials of particular characteristicsbut, in addition, by employing the laminating adhesive not only foradhering the various sheets or plies together but also Vfor effectingthe carton seal andproviding for its reactivation l? U andredistribution for such heat sealing functions. This is accomplishedthrough a novel initial distribution to specific localities of thecarton construction.

I have also found that the foregoing and additional objects of theinvention are accomplished by the provision of scored carton blanks andcartons and a novel-method` of forming the same, in all o f which areemployed an unprecedented quantity or thickness of thermoplasticadhesive laminant, and by providing such scored carton blanks andcartons from laminated sheet material having certain additionalrequisite characteristics, which carton blanks and cartons areadditionally provided with openings through atleast one ply of saidlaminated sheet material into the intercalated thermoplastic laminantadhesive in heat-sealing areas where the surface of an end, side, front,or other closure flap or face will oppose or opposes the surface ofanother ap or carton face towhich it is or is to be secured, whenbrought into juxtaposition therewith, lor alternatively withperforations extending through such a carton member from face to facethereof, especially where both surfaces of such closure member lie orwill lie in opposed facing relationship to surfaces of carton aps orother carton members when brought into juxtaposition therewith. By theemployment of substantially increased quantities of thermoplasticadhesive laminant, considerably in excess of those quantities employedpreviously for laminated sheet materials used in scored cartonconstruction, in combination with selected base sheet materials havingthe requisite openings, and by extrudhig to provide rivets or bodies ofadhesive, and by thus taking a direction quite to the contrary of thatindicated by established adhesive theory, I have found that I canproduce a carton seal which is ordinarily suiciently strong that, uponopening of the carton, the fibers of the basic sheet materials employedin the laminated sheet material are subjected to rupture rather than thelamination or the seal itself, in sharp contrast to cartons of asomewhat similar nature employed previously in which either the seal orthe lamination ruptures considerably in advance of rupture of the fibersof the base sheet materials of the laminate. As a consequence, thestrength of the lamination or seal in the cartons of the presentinvention does not become the limiting factor in determining the use oradaptability of the carton structure. In addition, the cartons of thepresent invention, when desired, can be made hermetically sealed andsubstantially leakproof to an extent not previously attainable inheatsealing cartons despite the -absence of any or substantially anyadhesive laminant on the exterior exposed faces of the carton.

According to the invention, the laminated sheet material employed in thecarton construction contains at least about titty-tive pounds andpreferably greater amounts of thermoplastic adhesive laminant perstandard 24 inches by 36 inches by 500 sheet ream of t-he laminatedsheet material. This permits unprecedented sealing characteristics. Inaddition, the base plies of the laminated Sheet material have a porosityof at least tive and preferably ten seconds. This permits the desiredextrusion and allows scoring and provision of necessary openings withoutfragmentation. This basic combination appears to be fundamental to theheat-sealing adequacy of the cartons of the invention, as more fullyexplained hereinafter.

Repeated attempts to form an adequate heat sealing carton fromrelatively open sheets, such `as porous tissues, have led only tofailure. When the thinnest sheet of a given lamination is too porous, anumber of unfavorable results are obtained. During lamination to theheavier, or to a like sheet, excessive bleed through the sheet occurs,allowing wax or other laminating agent to deposit on the surface of thesheet, which subsequently interferes with cutting, scoring and printing,especially when laminations are made with the amount of thermoplasticmaterial I have found necessary to form adequate carton seals.

Even though the wax or other thermoplastic adhesive may be limited tothe adhesive interfaces during laminating, such as by control ofviscosity of the laminant, I have found that the thermoplastic laminantis forced, during subsequent cutting and scoring, which involves use ofhigh pressures over limited areas, through the porous sheets at scoredor cut areas, thus building up on dies and cutters to the point ofrendering these operations diicult if not impossible. Since the poroussheets are lacking in strength, tearing andi breaking often accompaniessuch sticking.

It has also become evident, through investigations of the factorsinvolved, that the use of porous papers or preperforated sheet materialsresults in a general over-all migration of considerable quantities ofthe thermoplastic adhesive during heat sealing, which is undesirablewhen use of the adhesive in predetermined areas, and especially in theform of extruded rivets or bodies of adhesive, asin the cartons of thepresent invention, is required.

For the above reasons I have found it necessary to use sheets having aporosity, as dened by the air resistance test of TAPPI method T460 M-49,of at le-ast tive seconds and preferably ten seconds or above. Bycontrast, I have found that porous tissues, or like open sheets, oftenhave a porosity value of less than one, and seldom greater than two,seconds.

I' have also found porous tissues lacking in the strength necessary towithstand scoring Iand subsequent folding, and my thinnest paper sheetsare therefore generally chosen with a Mullen dry burst strength of tenor above, 'and preferably fifteen -o-r above, gas determined -by TAPPIprocedure T403. However, strength may not be critical, and is generallynot as critical as porosity, especially when stretchable materials suchas creped papers, or plastic hns such -as polyethylene or polyvinyl4chloride films, are used as the thinnest sheet of the laminate.

The requisite openings, interstices, or apertures in one or more plies.of the carton member or members in accord with the present inventionmay be and preferably are slits or cuts, and their disposition may beeither longitudinal, transverse, or diagonal, and when present in morethan one carton member, or when upon folding of the carton the slits orcuts in a ply of one member oppose the slits or cuts lin an opposing plyof another carton member, they may be the same or different, in anycombination of longitudinal, transverse, or diagonal disposition,including diagonal `sl-its in the ply of one member `and reversediagonal slits or cuts in the ply of the other member, e.g., anunderlying ap member. The slits or cuts may be of the laforesaid types,whether only one, or more lthan one, ply of one or more than one cartonmember is slit or cut, and whether or not the said slit or cut plies areopposed and in contact with each other upon folding of the cartonmembers. When fperforations are present, said term being understood toindicate openings which go through the entire sheet material from yonesurface thereof to the other, i.e., through all plies of the sheetmaterial, such perforations may be slit, cut, punched, square,rectangular, circular, oval, triangular, diamond-shaped, dogeared,elliptical, or of any other type or shape and, when slits or cuts orrectangles or the like, may be longitudinal, transverse, diagonal, Ianycombination thereof, or of any other direction or conguration, and maybe imparted to the carton member with or without removal of a part ofthe sheet material of construction as by drilling or punching. Ifopenings in only one ply of sheet material are present, these may be inshapes and sizes other than slits or cuts, and may be of anycontiguration or type mentioned for perforations, but are preferablyslits or cuts, and usually at least one-sixteenth inch apart or.approximately twelve to the inch, and .at any rate ordinarily no lessthan two leads (.056 inch) apart. In addition, any carton Hap or othermember, but preferably an intermediate flap, may

a, lodava 7 be provided vwith a :combinationrof openings (such 'asslits, or cuts, or circular -cutouts, or the like) in one ply of theflap Iand `also perforations entirely through the 'same iiap, or theflap may be provided with openings such as aforesaid in both outer pliesthereof, with or without removing laminant or other mater-ial ofconstruction, or lany other combination of openings and/or perforationsmay be employed on either or vboth surfaces of a single flap or othercarton member as the problem of laminan-t desirability in a particular.area may require. Whether the openings are present in only one ply orin more than one ply, and whether in the form of perforations, slits,cuts, or the like, the openings are ordinarily at least 1/32 and usuallyat least 1/16 of an inch in at least one dimension, and in any eventhave dimensions greatly exceeding the dimens-ions of the pore openingsnormally present in the fibrous sheet materials employd in the laminate.

I have found it preferable to provide the necessary openings or foramen,usually in the form of slits or perforations, and any desired cut edges,for the extrusion of the laminating adhesive used in the construction ofmy heat sealing cartons, at some stage after the laminating step, andduring or after the formation of scores and cutouts necessary vfor theVdelineation of the carton structure, and preferably atte-r the printingof any required indicia or artwork which must be registered with thecarton faces. lu this Way the means for extrusion of the laminating.adhesive a-re located in exactly the desired zones as required for theformation of the desired bond or seal, and laminant adhesive is notrandomly extruded as wouldV be the case if openings were placed in oneor both of the sheet materials in advance of the laminating step.Furthermore, due to the character of the slits or perforations pr-ovidedand the amount of adhesive used as laminaat, it is necessary that theybe provided following the lamination step, as this prevents unwantedtransfer of the molten hot melt used in the laminating .step :throughthe sheet prior to the moment of its intended use in sealing of thecarton.

inasmuch as the functioning of the :sealing and laminating adhesive ofmy carton construction does not depend on the principle of dilierentialmigration by absorption, but rather on extrusion under heat or heat andpressure, the choice .of she-et materials which can be used is quitebroad, 4as they can be of equal or differing calipers and porosities. Ingeneral, l prefer t-o use a lighter sheet for -the inside ply of thelaminated sheet material, although for some `applications the heaviersheet may form the inside surface of 4the carton Wall. When the heaviersheet is placed on the side which will become the outside surface of thecarton, it will generally be a pigment coated paper or paperboard toprovide a good printing surface, and to obtain other advantages whichwill be hereinafter described. At least one sheet of the laminated sheetmaterial must have sufficient strength to provide structural rigidity,and ordinarily both sheets will have suiiicient strength for thispurpose and will each exceed about ten pounds per inch in tensilestrength as determined by TAPPI method T404m. In some cases, theVtensile strength of one or both sheets -will be much higher thenrequired for specific packaging applications. The thickness of the sheetmateria-ls employed in the laminated :sheet material will generallyrange from about .002 to abouty .016 inch, with a thickness of laminantfrom about .004 inch to about .015 inch but usually ranging from about.004 to about .008 inch. While the thickness of the sheet materials asmentioned is usually from about .002 to .016 inch, I may employpaperboard sheet material as one ply of the laminated sheet which has athickness as great as .03 inch. n

Any or all sheet materials used as base sheet material stocks for:production of the starting laminated sheet material may be treated inany of various Ways, such as by printing, treating for grease-proofnessor wax hold-out,

glossing, and the like, and such treatment'will ordinarily. be appliedprior toV lamination. Representative sheet materials include, inaddition to paper and paperboard, parchment papers, papers containingfoil mounted thereon, grease-proof papers, glassine papers, non-wovenfabrics, and the like. Y

As further indica-tive ofV base material lstocks which are suitablev forincorporation into laminated sheets vfor sco-ring and cutting intocarton blanks and erecting into cartons according ,to the presentinvention, there may be mentioned the usual `paper or paperboard sheets,such as made on a cylinder machine or a multiple-headboxFourdriniermachine, lhaving aV number of plies, or heavy paper'sheetshaving only aV single ply. Generally speaking, the base. sheet stock maybe'any fibrous cellulosic or synthetic sheet, but in some cases mayinclude foils or lms as one ply thereof. Aluminum foil may sometimesadvantageously be'used `for one ply, especially when the ply is tobecome the inside surface of a carton.v ln such cases they aluminum foilmay be and preferably is mounted on a light paper before gluing orlaminating to a second brous ply, f-oil side in. For highest possiblemoisture-vapor proofness, these sheet stocks `may be additionallyproofed, including for example dry waxed, semi-waxed, or surface waxedpaperboard or paper materials, i-or polyethylenecoated materials, or thelike. The cartons of the invention are fabricated of such laminatedsheet materials, illustratively paperboard wax-laminated to paper, andwill in general be fibrous sheets laminat-ed to each other or to foilswith suitable laminating materials as hereinafter more fully described.VY

t in `thesheet materials employed for the formation of my heat sealableand especially leakproof cartons, the ability of the laminating adhesiveto extrude through slits and raw Vedges provided in certain preselectedVareas of the carton construction is essential. VWhen a leakproof orhermetically sealed carton is required, l have found that it isnecessary to extrude laminating adhesive through suchsslits,perforar-tions and edges in sufficient amount not only to heatY seal atcontiguous surfaces, but also to cover or block the raw cut edges offibrous sheet materials used in fthercarton construction to preventmigration by wicking of moisture, .water-vapor, liquids, or greasesthrough the closure aps or seams of the carton construction. Likewise,even when a leakproof carton is notV required, as when a tacked ortamperproof Vcar-ton is of interest, a satisfactory bond between thecarton member desired to be secured requiresthat a certainminimumquantity of thermoplastic laminant adhesive be present to providethelrequisite bodies of adhesive, by extrusion through one or more pliesof the car-ton construction, which are necessary for a satisfactorydegree of adhesion.

As thermoplastic adhesive laminant for uniting the plies of laminatedsheet materials which are employed Vin producing t-he carton blanks andcartons of the present invention, the so-called hot-melt adhesives arepreferred. Moisture-vapor-proof hot melts based on petroleum waxes areespecially suitable, as these have a highjdegree of plasticity andflexibility. Hot melts basedy on mierocrystalline Vwaxes are especiallypreferred. Additional representative laminant adhesives include` (A)microcrystalline waxes of .any origin, e.g.,-Loui-siana,f Pennsylvania,or Mid-Continent origin,'and/or paraiiin waxes modified with:` (l)synthetic polymers such as butyl rubber, polyisobu-tylene, polyethylene,copolymers of vinyl acetate and ethylene, y(2) aluminum stearato, (3)hydrophilic ladsorbents, (4) surface activators, (5) terpene resins,

(6) ester gums, (7) rosin derivatives, and the like; (B) low molecularweight polymers `such .as V(1) polystyrene of 4,060 to 20,000 MTW., (2)polyethylene of 2,030 to 12,000 NLW., (.3) polyterpenes,.(4) isoprenepolymers, (5) chlorinated natural and :synthetic rubbers, (6) naturalrubbers, and the like; (C)` cellulose Vderivatives such as '(1) ethylcellulose Vcompositions and Vmixtures thereof with resins, waxes andplasticiz'ers, (2) vnitrocellulose thermoplastics, (3) celluloseacetates or other esters and mixtures .thereof with resins and the like;all of which may be suitably inodied with various other resins and withplasticizers, according to conventional knowledge and procedure of theart.

The thermoplastic laminating adhesive employed in making the startinglaminated sheet material -should have the usual flow characteristics ofa thermoplastic and may, for example, have a viscosity of at least about75, and

preferably at leas-t about 150, centipoises in the range of from aboutten degrees to about fifty degrees Fahrenheit above its softening point,c g., at a temperature of about 220-270 degrees Fahrenheit, as measuredby a Brookeld synchroelectric viscometer or other rotational viscometerat a spindle speed less than ten r.p.m. As previously stated, hot meltcompositions based on hydrocarbon and especially petroleum waxes aresuitable, preferably those based on microcrystalline waxes, and thesemay be increased in viscosity by admixture therewith of viscositybuilders such as polymers or ethylenically unsa-turated hydrocarbons,natural gums, gelling agents, or a hydrous adsorbent powder incombination with a surface activator, especially inorganic gelling.agents such as hydrated attapulgite or the like -together withnitrogen-containing surface ac-tivators, especially fatty-acid -amidesand alkyl Quaternary ammonium salts, or any other viscosity buil-deryindicated previously. The latter type of wax composition, involvingcombinations lof microcrystalline or other hydrocarbon waxes withhydrated adsorbents and longc-hain parafiinic surface activators, suchas the types mentioned, prepared by expulsion of water of hydration fromthe adsorbent lin the presence of the surface activa-tor, are disclosedin my copending US. patent application Serial Number 133,490, tiledAugust 23, 1961, and are preferred because of their thixotropicproperties, although it is not essential that these be employed as manyothers are suitable. The density of the adhesive laminants employed willordinarily be from .about 12 to about 25 or more pounds per ream(24-x36x500) per each .001 inch of thickness thereof.

I have found that there is a limiting lower level of the amount orthickness of the thermoplastic adhesive laminant to be used in thelaminated sheets for my carton construction. In general, I have found itdesirable to have uninterrupted laminant exceeding the thickness of thebase sheet of the laminate around and through which the larninant willbe extruded. In any event, however, the .adhesive will be present in anamount of at least about fifty-five and preferably at least sixty poundsper ream (24x36x500 or 3060 square feet). This latter amount is usuallysuilicient to provide a thickness of laminant in lexcess of about .G94inch. With this thickness of laminant, there is suihcien-t adhesivematerial to extrude through the lopenings provided in the ply or pliesof the flap and/ or other carton members, and when present .also throughthe recessed edges of intermediate flap members and into the area ofopposed facing relationship between -outer and inner tlaps in the areaof overlap of such intermediate flap or flaps by an outer flap. Thisamount of laminant is also suflicien-t to extrude out of the cut edgesof top or outer ilaps and, if desired, other flaps, thereby -toeffectively seal the same. However, it is to be understood that greaterthicknesses `of laminant, even exceeding the combined thickness of thebase sheet materials, may be employed if desired. When both sheets arerelatively porous, it may be necessary and is frequently advantageous toemploy laminaat in an amount in excess of the amount necessary tosaturate both sheets, which is generally about one fourth of theircombined thicknesses.

I have moreover found the laminated sheet materials of my copending US.patent application, serial Number 133,521, led August 23, 1961, ideallysuited for use in the construction of heat seal-ing cartons according tothe present invention, although not essentially therefor.

IIn the heat sealing cartons and carton blanks of the present invention,it is also advantageous to provide a `driving force to assist extrusionof the laminating agent into the desired locations for seal-ing of thecarton, especially when a hermetic seal is desired. Ordinarily, theextrusion can be accomplished by heat ror heat and pressure alone,whether sealing with or without a mandrel. However, in certaininstances, as in providing the top closure tack or seal of a lledpackage Where the application of excessive pressure would distor-t thepackage, I have found it desirable to have a heat-activated drivingforce, such as a volatilizable material, present in the outside ply ofthe laminated sheet material, that is, in the ply opposite to the plycarrying the openings through which the extrusion of adhesive isdesired. `This driving force can ordinarily be simply provided by theaddition of an aqueously or otherwise deposited coating, such as a clayand/ or pigment bound by any one or more of various adhesives of thestarch, casein, or latex variety. Certain inks can also be chosen whichcontain or occlude volatile materials. It is also possible to includedriving materials in a sheet material used in the lamination during itsproduction, as 1in the papermaking step, or to provide suffrcently highmoisture content in the paper to provide the desirable driving forceduring heat sealing. During the heat-sealing step, such materialsapparently assist by creation of sufficient vapor pressure to aid inextrusion and redistribution of the laminating adhesive without theapplication of excessive amounts of external force. Although I do notunderstand completely all the fa-ctors involved, I have found theinclusion of mineral clays in the sheet or in the coating of the sheet,constituting the ply Iof laminated sheet material opposite to the plyprovided with openings into the intercalated thermoplastic laminantadhesive layer, to be particularly effective, especially when an outertlap is involved, Iin which case the driving force from the volatilematerial in the upper ply 'of t-he outer flap, or lin the coating of theouter hap, mate- Irially assists 4in the extrusion of the adhesivethrough the interstices provi-ded in the inner ply of the llap uponapplication of heat to the outer ply or surface of such outer ilap, andthus cooperates in accomplishing 4the desired extrusion withoutapplication of undesirable pressure to the carton structure. Theprovision of such a driving material Iis most simply and convenientlyaccomplished by including the same in or in a coating on the base sheetmaterial which is .to be the outer ply of the formed carton. Thisembodiment -of the invention, e.g., in which mineral clays .and/ orpigments are employed in combination with the base sheet materials, isespecially valuable in cases where two base sheet materials ofapproximately equal caliper are employed.

Reference is now made to the accompanying drawings which show exemplary-embodiments of certain carton blank and carton constructions andarrangements of parts which may be e-mpl-oyed according to theinvention, without any limitation of the invention thereto, wherein thesame numerals refer to the same parts, similar parts of differentfigures are -denoted by like numbers except for a -hundred place digit,and wherein:

FIGURE 1 is an enlarged cross-sectional view of a portion of a laminatedsheet material utilizable according to the invention.

FIGURE 2 is a plan view showing the printed side of a carton blankembodying the present invention.

FIGURE 3 is a broken plan view showing the reverse or heat-sealing sideof the carton blank of FIGURE 2.

FIGURE 4 is a top or bottom view of any erected and sealed cartonconstructed in accord with the invention.

FIGURE 5 is an exaggerated cross-sectional view on line V-V of FIGURE 4,considering FIGURE 4 a top view, showing one version of the erected andsealed carton, having been erected from the carton blank of FIG- URES 2and 3, with ya part thereof shown in broken elevation.

. line r"i/II--VII of FIGURE 4, considering FIGURE 4 a top View, showinganother 'form of the erected and sealed carton, having been erected from.the carton blank ot FIG- URE 6, with a part thereof shown in brokenelevation.

FIGURE 8 is a partial plan View oi one side of another carton blankembodying the invention.

FIGURE 9 is an exaggerated cross-sectional view on line IX IX of FIGURE4, considering FIGURE 4 a top View, showing 1ano-ther form of theerected and sealed carton, having been erected from the carton blank ofFIGURE 8, with a part thereof shown in broken elevation.

FIGURE 10 is a partial plan view-of one side ot another carton blankembodying the invention.

FIGURE 11 is an exaggerated cross-sectional view on f line Xl-XI ofFIGURE 4, considering FIGURE 4 a top View, showing `a urtherfform of theerected and sealed carton, having been erected from the carton blank ofFlf- UIE 10, with a par-t thereof shown in broken elevation;

FIGURE 12 is a partial plan view of the inner or heatsealing side otanother carton blank embodying the invention.

FIGURE 13 is a partial plan view of the outer or reverse side of thecar-ton blank of FIGURE l2, also having heat-sealing areas. t

'FIGURE 14 is an exaggerated cross-sectional view on line XIV-XIV ciFIGURE 4, considering FIGURE 4 a top view, showing an additional form ofthe erected and `sealed canton, having been erected from the cartonblank of FIGURES '12 and 13, and with a part thereof shown in brokenelevation. Y n

FIGURE 15 is a partial plan view of the outer and heat-sealing side ofanother carton blank embodying the invention.

FIGURE 16 is an exaggerated cross-sectional view on line XV-XVI of`FIGURE 4, considering FIGURE 4 a top view, showing a further form ofthe erected and sealed carton, having been erected from the carton blankof FIGURE 15, with a par-t thereof shown in broken elevation.V Y

FIGURE 17 is a partial plan view-of the inner or heatsealing side ofstill .another carton blank embodying the invention.

FIGURE 18 is a .partial plane view of `the outer or reverse `side of thecarton blank of FIGURE 17, also having a heat-sealing area.

FIGURE 19 is 1an exaggerated cross-sectional view taken yon line XIX-XIXof FIGURE 4, considering FIGUREV 4 a top View, illustrating yet anotherform of the erected and sealed carton, having been erected from thecarton blank of FIGURES '17 and 18, showing the intersections of thediagonal cuts in the Iilaps of the carton blank of FIGURES 17 and 18,and with a part thereof in broken elevation.

FIGURES |20 and 21 are partial plan views of additional carton blanksembodying the invention. v

FIGURES 22 through 25 are partial plan views of additional carton blanksembodying the invention, in which the carton blanks are viewed fromtheir inner or heat-sealing side.

FIGURE 26 is a broken isometric view of a carton embodying the inventionerected from a carton blank embodying the invention showing theheat-sealing areas thereof exposed to view.

Referring now to the drawings, FIGURE 1 isV an venlarged cross-sectionalView of a portion of a laminated sheet material -10 utilizableaccor-ding to the invention,

as it might be formed by laminating'a iifty pound per ream (24 x 36 x500) 0.0035 inch thick dry waxed paper sheet 11 to a .012 inch thickpaperboard sheet i12 with .0065 inch of thermoplastic laminatingadhesive 12, as shown -in Example 1 following. l

FIGUR-E 2 shows a plan view of the -outer printed side of carton blank2i) embodying the invention, as viewed having the thicker' or paperboardplie 13 of laminated sheet material 11D facing the viewer. The generallyrectangular precut blank il includes rectangular frontV face panel 21,rectangular back tace panel, rectangular right yhand end panel 23, andrectangular left hand end pan-el 24 between frontV tace panel 2,1 andback face panel 22. Glue ilap 25 is adjacent to 4and integral with lbackface panel 22.1Y Y

Blank Ztl includes front bottom flap 2d, back bottom iiap 27, and bottomend flaps 2d and 29, alladjacent to and integra-l with the front, back,and end panels respectively. T he blank is also provided with front topflap 31, back top hap 32, and top end flaps 33 and 34, all respectivelyadjacent to and integral with the front, back, and end panels. Glue ilap25 is provided with Ybottom and top extensions 3@ and 35, which intheassembled carton are attached t-o and -fold with bottom and top endflaps 2% and 33, respectively.

Blank 2@ is scored to 'provide fold l-ine 36 between front face panel 21and right hand end panel 23 and to .provide fold line 37 lbetween frontface panel 21 and left hand end panel 24 and t-o provide fold line 38between back face panel 22 and lett hand end panel 24 and fold line 39between back face panel 22yand glue ap 25. Score or fold lines Sethrough 39 are all'parallel and extend transversely acrossblank 2t?.

Blank Ztl is also scored longitudinally in spaced relation to one edgethereof to provide fold line 4@ between front face panel 21g-and frontbottom iiap 2t, `fold line 41 between lback face panel 22 and backbottom flap 27, and lfold lines 42 'and 43 between end panels Z3 and 24and endv bottom tia-ps 2S and 29, respectively. The blank is moreoverprovi-ded with transverse cuts between its edge and the longitudinalfold line formed by score lines 40 through 43 between bottom iiaps 26and 28,26 and 29, 27 and 29,'and 'between back bottom flap-27 andextension 3d, to permit the bottom naps to be folded inwardly at rightangles with respect to their adjacent panels.

Still refer-ring to FIGURE 2, the carton Folank Ztl is also scoredlongitudinally in spaced relation to its opposite edge toprovide a foldline `45 between front face :panel 21 and front top flap 31, to provid-efold line .45 between back face panel 22 and back top ap 32, and toIprovide fold lines 47 `and 148 `between end panels Z3 and Z4 and topend flaps 33 and The blank is moreover provided Vwith transversecutsextending from its edge to the fold lines ybetween top flaps 31 and33, 31 and 34, 32 an-d 34, and between back top l,flap 32 and exten-`sion 35, to permit the top iiaps to be folded inwardly at right yangleswith respect to their adjacent panels.

As shown, end flaps 2S, Z9, 33 and 34 have a lateral reach which isslightly less than that of front land back 4top aps 2d, 27, 31 and 32,but which lateral reach is approximately one-half the width of front topand bottom liaps 26 and 31.

Glue iiap 25 is joined to back face panel 22 along fold line 39 vand isalso scored in spaced relation to its edges to provide fold lines 44 and49, which are-respectively extensions of fold lines 41 and 46, alongwhich fold lines 44 and @Xgl-ue flap 25 is joined .to its bottom and topextensions 3@ and 35, respectively..

As will be noted from FIGURE 2, back` bottom flap 2.7 and back topiiap32 are recessed or partially cut away at their lateral edges Sti and S1and 52 and `53, respectively, making these flaps of lesser width andarea than front top and bottom flaps 2o and 31, and as shown have acurved reach 54 in each'of their lateral edges so as to impart a tapertheretofllhese flaps Z7 and 32 are of full lwidth at their respectivejunctures with back-tace panel 22 along sco-re lines 41 and 46, but ofIredilrced ,width at their longitudinal edge..v The .taperedfaspect ofback V'bottom -and top flaps 27 and .32, in which said ilaps are of adiminished width with respect to front top and bottom flaps 26 and 31,'constitutes a preferred manner of construction of theilaps.

As viewed in FIGURE 2, printed ltext -or legend is present on front andback face panels 21 and 22, as at 55, on right and left hand end panels23 and 24, as at 56, Iand on front top and bottom flaps 26 and 31, as at57, all in register with .the various score lin-es, outs, and panels.

Referring now to FIGURE 3, which is a broken plan View showing thereverseor heat-sealing side of carton blank 2li (of FIGURE 2), as'viewed showing thinner ply 11 of laminated sheet material 1G facing theviewer, all of the members of the carton blank observed from FIGURE -2are also appa-rent in FIGURE 3, in their reverse position, and areidentically numbered.

Still referring to FIGURE 3, in addition to all the elements except theprinted indicia observed from FIG- URE 2, there will -be seen transverseslits 60 an-d longitudinal slit 61 in each of front botto-m and topllaps 26 and 31 and corresponding slits 62 and 63 in back lbottom andt-op ilaps 27 and 32, which slits extend through thinner or paper ply 11of laminated sheet material 1d from which carton blank 20 is constructed(see FIGURE l). while as shown in FIGURE 3 the inner ply 11 of laminatedsheet material 1li is the thinner of the several plies making uplaminated sheet material 1li, it is not essential that the inner sheetreceiving slits or cuts 60 through 63 should be the thinner ply, as itcould also 4be the thicker ply, for example 13 in FIGURE 1 (see FIG-URES 13 and 18). As shown in FIGURE 3, slits or cuts `6l) through 63extend through thinner or paper ply 11, providing interstices 4or`openings in ply 11 from the 'inner layer of thermoplastic adhesive`laminant 12 (see FIGURE 1) to the exterior of sheet `or ply 11.

FIGURE 4 is a top or bottom view of any erected and sealed cartonconstructed in accord with the present invention, and is included solelyfor purposes of providing a cutting line upon which the cross-sectionalviews of subsequent iigures may be taken. When viewed from the top orbottom, as in FIGURE 4, an erected and sealed carton constructed inaccord with the present invention has substantially no differentappearance than any other conventional carton. The top or bottom of anyerected and sealed carton constructed in accord with the invention isshown in FIGURE 4 as 64, and the front face panel of any such carton isindicated at 65. For purposes of the following FIGURE 4 will beconsidered a top view.

FIGURE 5 is an exaggerated cross-sectional view on line V-V of FIGURE 4,showing a carton according to the invention, having been erected fromthe carton blank of FIGURES 2 and 3 and sealed.

From FIGURE 5 can be seen left hand end lap 34, right hand end panel 23with its end tlap 33, back top flap 32, left hand end flap 34, and fronttop flap 31, each with paperboard ply 13 and paper ply 11 and layer ofintercalated adhesive laminant 12. Glue ap 25 and extension 35 are alsoapparent. nterstices 6d and d2 in paper ply 11 of front top flap 31 andback top flap 32 are apparent. Thermoplastic adhesive laminant 12 fromfront top llap 31 and back top flap 32 has extruded respectively throughinterstices 60 and $2 forming respective bonds between upper orpaperboard ply 13 of front top flap 31 with upper or paperboard ply 13of back top ilap 32 and between upper or paperboard ply 13 of back toplap 32 with upper or paperboard ply 13 of end llap 33. Adhesive 12 fromfront top flap 31 has also extruded outwardly at the cut edge of fronttop lap 31, forming a seal over both paperboard 13 and paper 11 plies oftop flap 31 at their respective cut edges. Due to recessed edge 52 ofback top tlap 32, adhesive 12 from front top flap 31 and back top flap32 has extruded downwardly .and outwardly to form a direct bond betweenupper or paperboard ply 13 of top flap 31 and upper or paperboard ply 13of end lap 33, thereby also sealing oil the cut edges of plies 11 and 13of back top flap 32 at flap edge 52. No cut `edges are exposed forwicking, but all are sealed ot by thermoplastic laminant 12. Front topap 31 is bonded not only to back top ap 32 by adyand glue flap 125.

hesive 12 through interstices 60 but back top tlap 32 is likewise bondedto end llap 33 by adhesive 12 through interstices 62, and front top flap31 is bonded directly to end lap 33 through adhesive 12 which hasextruded through interstices 6d and through cut edge 52 of back top tiap32. Interior of the carton body, adhesive 12 has extruded out of the cutedges of end flaps 33 and 34, thereby forming a bond between them andwith back top flap 32 from which additional thermoplastic laminantadhesive may extrude through interstices 62. Under sutlicient heat orheat and pressurelaminant 12 may also extrude out or" and seal the lcutedge of glue flap extension 35.

In FIGURE 6 is shown a partial plan view of the heatsealing side ofanother carton blank embodying the invention, formed from laminatedsheet material 11d, with thinner or paper ply 111 facing the viewer.Blank 12@ includes front face panel 121, back face panel 122, right handend panel 123, and left hand end panel 124. Parallel transverse scorelines 136, 137, 138, and 139 are respectively between front face panel121 and right hand end panel 123, between front face panel 121 and lefthand end panel 124, between back face panel 122 and lett hand end panel124, and between back face panel 122 Front top flap 131 is integral withand attached -to front face panel 121 along longitudinal score line 145,back top ap 1321's integral with and attached to back face panel 122along longitudinal score line 146, and 4right hand and left hand topflaps 133 and 134 are integral with and respectively attached to righthand and left hand end panels 123 and 124 along longitudinal score lines113.7 and 14S. Glue flap 125, which is integral with and attached toback face panel 122 along transverse score line 139, is also integralwith and attached to extension 135 along longitudinal score line 149.All of the longitudinal score lines are extensions of each other.Transverse cut are also provided between the edge of blank andlongitudinal fold line formed by score lines 145 through 149 between topflaps 131 and 133, 131 and 134, 132 and 134, and between 132 andextension 135, to permit the aps to be folded inwardly at right angleswith respect to their adjacent panels. Back top ilap 132 is againrecessed or cut away at its lateral edges 152 and 153 so as to be ofdiminished width at its longitudinal edge, with respect to back facepanel 122, but being `of full width at its juncture with back tace panel122 along score line 146, and angled along each of lateral edges 152 and153, as at 154, so as to impart a longitudinal edge of iiap 131.Transverse cuts 16d are provided in paper ply 111 of front top flap 131as is longitudinal slit or cut 151 in spaced relation to thelongitudinal edge of tlap 131. Tranverse cuts 169 are parallel andextend from their origins equally spaced from longitudinal cut 161 totheir parallel termini all equally spaced from score line 145.

FIGURE 7, an exaggerated cross-sectional view 0n line VII-VII of FIGURE4, shows a carton erected from the carton blank of FIGURE 6 and sealed.From FIG- URE 7 can be seen right hand end panel 123 with its end flap133, left hand end hap 134, back top flap 132, and front top ilap 131,each with its paperboard ply 113 and paper ply 111 together withintercalated thermoplastic adhesive laminant 112. Glue tlap withextension are also apparent. Interstices 166 in paper ply 111 of fronttop flap 131 are apparent, and adhesive 112 from top ap 131 has extrudedthrough interstices forming a bond with the upper or paperboard ply 113of back top ilap 132. Adhesive 112 has also extruded downwardly throughinterstices 160 in front top ap 131 and outwardly at cut edge 152 ofback top ap 132, as well as outwardly at the cut edge of front top flap131, forming a seal over both paperboard 113 and paper plies 111 offront top flap 131 and back top flap 132 at their respective cut edges.Due to recessed lateral edge 152 of back top flap 132, adhesive 112forms a direct bond between upper or paperboard ply 113 of iront topiiap 131 and upper or paperboard ply 113 of end flap 133. No

cut edges are exposed for wicking, all cut edges are sealed oli byadhesive 112, and top lap 131 is bonded by adhesiveV 112 not only toback top flap 132 through interstices 1d@ but also directly to end tlap133. Interior of the carton body, adhesive 112 has extruded out ci cutedges of end iiaps 133 and 13d, thereby sealing oil these cutedges andsecuring them to each other and to back top iiap 132. Under sufficientheat and pressure, adhesive 112 may also extrude out of the cut edges ofglue iiap extension 135, thereby also sealing oit the same.

Referring now to FIGURE 8, this partial plan View of one side of anothercarton blank embodying the invention shows thinner or paper ply 211 ofcarton blank 221i constructed from laminated sheet material 21) facingthe viewer. Transverse score line 236 separates front face panel 221 andglue ilap 225, score line 237 separates front face panel 221 and righthand end panel 223, while score line 233 separates back face panel 222from Vright hand end panel 223 and score line 239 lies between back facepanel 222 and left hand end panel 224. All transverse score lines areparallel and all panels are rectangular. Front top flap 231, which willbe the top or outer flap in the erected carton, back top ap 232, whichwill underlie front top ilap 231 in the erected carton, and right handand left hand top flaps 233 and 234s,r the end flaps, are all shown, asare glue iiap 225 and its extension 235. Longitudinal score lines 245,243, 247, 2413, and 249 are all extensions of each other and aredisposed in spaced relation to the edge of blank 221i. The usualtransverse cuts are provided between the edge of blank 220 and thelongitudinal score lines between front top ilap 231 and right hand topflap 233, between front top ilap 231 and extension 235, and between backtop flap 232 and end iiaps 233 and 234.y

Back top ap 232 is again shown as recessed or cut away at its lateraledges 252 and 253 which are angled as at 254 to provide a width of backtop ap 232 at score line 246 which is the same as the width of back facepanel 222, although of diminished width at the longitudinal edge of flap232. Back top flap 232 is provided with minute (eg, 1/16 inch in length)perforations 266, diagonally disposed in flap 232 in spaced relation toits edges, which are slits or cuts which penetrate not only inner ply211 of sheet material 210, but also the layer of adhesive 212 (notshown) and outer ply 213 (not shown) on the opposite side of the sheetmaterial 21). ln this manner back top flap 232 is provided withperforations or holes which extend from one face of ap 232 to the other.

FGURE 9 shows an exaggerated cross-sectional view of a carton erectedfrom the carton blank of FIGURE 8 and sealed. From FIGURE 9 are seenfront top ilap back top ap 232, and end aps 233 and 234, end iiap 233being attached to right hand end panel 223. Thermoplastic laminantadhesive 212 has been extruded by the application of heat, or heat andpressure, through the interstices 266 in both paperboard 213 and paperplies 211 of back top iiap 232 and through the cut edge 252 of back topflap 232, thereby effectively sealing upper ply 213 of back top flap 232to bottoni ply 211 of front top iap 231, sealing the bottom ply 211 ofback top ap 232 to top ply 213 of end llaps 233 and 234, sealing thebottom ply 211 of front top iiap 231 to top ply 213 of end flap 233through interstices 266 and also directly in the area in which top' iiap231 overhangs back top iiap 232 outside its recessed lateral edge 252iAdhesive 212 has also been extruded through the cut edge of top iap 231,and from the cut edgesy of end ilaps 233 and 234 which are joined byextruded adhesive 212 to each other and to ap 232, thereby sealing offall cut edges against wicking and securely binding all of the closure'members or ilaps of the carton to each other.

maaar/a -The carton blank 323 shown in partial plan view with paper ply311 of laminated sheet material 310 facingthe viewer in FlGURE l0illustrates a diierent embodiment of the invention and is otherwisesimilarjto the carton blanks of previous figures. Front :tace panel 321and back face panel 322 are joined to right hand `end panel 323 alongparallel transverse score lines 337 and 333, respectively, and frontface panel 321 is joined along transverse score line 336 toV glueiap325, whilepback tace panel 322 is joined along transverse score line 339to lett hand end panel 32d. Rectangular face and end panels are joined`to their respective top ilaps along longitudinal score lines 345 through343, and glue tiap325 is joined to its extension 335. along score line3413, all of which score lines 345 'through 349 are extensions of veachother. lFront top flap 331, back top kflap 332, and end tiaps 333 and334 are all joined to their-respective front, back andV end panels alongsaid longitudinal score lines, and are separated from each other by theusual transverse cuts extending from the longitudinal edge of blank 32)to said longitudinal score lines. Front topV iap 331 is also separatedfrornextension 335 by such transverse cnt. Right hand and left hand endflaps 333 and 33d` are provided with generally diagonally arrangedperforations 367, in the form of slits or cuts which extend through thesurface oi the inner of paper ply 311 facing the viewer through theintercalated layer of adhesive 312 (not shown) and through the surfaceof the outer or paperboard ply 313 (not shown), thatis, from one face ofiaps 333 and 334 to the other. These flaps 333 and 334 are shown ashaving a lateral reach approximately one-half the longitudinal width offront top flap 331. Back top flap 332 is again of diminished width incontrast to top flap 331, in this case being recessed or cutback at eachof its lateral edgesV 352 and 353 so as to be of a lesser widththroughout its entire lateral reach than back face panel 322 to which itis joined along score line 3ft-6 to permit it to fold Yinwardly of thecarton end panels 323 and 324 (as shown in FIGURE ll).

An exaggerated vcross-sectional View, along line XI-XI of FIGURE 4, of acarton erected from the carton blank of FGURE l0 and then sealed, isshown in FlGURE l1. in this case, back top iiap 332 is innermost oi theY through interstices 367 in end aps 333 and 33d, as well as betweenupper ply 313 of end flaps 333 and 334 and lower ply 311 of front topiiap 331, and that adhesive 312 has likewise formed a bond betweenvupper ply 313 of back top hap 332 and lower ply 311 of end flaps 333and 334i. Adhesive 312 has also extruded outwardly through the cutlateral edge 352 of back top ilap 332, thereby forming a bond with innerply 311 of right hand end panel 323, and has likewise. extrudedoutwardly from iront top iiap 331 to form a seal over the eut edges ofboth plys 311 and 313 of front top ilap 331, thus sealing the saidcarton edges ofr against wicking, .the various closure members beingotherwise securely sealed to each other. At the juncture between endflaps 333 and 334, adhesive 312 has extruded `from theV cut edges,forming a bond therebetween.

FXGURES l2 and 13 are partial plan views of the two sides of anothercarton'blank 42d embodying the invention, showing respectively theinside of Vthe carton as it will be formed -with paper ply 4111 oflaminated sheet material 413 facing the viewer in FIGURE l2 and withpaperboard ply 413 facing the viewer in FIG- URE 13..

The various parts of blank '420 as shownin FlSGURE l2 17 correspond tothose shown for carton blank in FIG- URE 3 and the various parts ofcarton blank 42d shown in FIGURE 13 correspond to those shown for cartonblank 2@ in FIGURE 2, except for the heat-sealing areas and the factthat the lateral edges of back top flap 432 are not recessed.

Transverse cuts or slits 463 are provided in paper ply 411 of front topap 431 as is longitudinal slit or cut 4151 located in spaced relation tothe longitudinal edge of ilap 431. Transverse cuts 460 are parallel andextend from their origins equally spaced from longitudinal cut 451 toparallel termini all equally spaced from score line 445. The transversecuts 469 closest to the lateral edges of flap 431 extend into and areintegral with longitudinal cut or slit 461.

In FIGURE 13, transverse cuts 462 and longitudinal cut 463 are providedin paperboard ply 413 of back top flap 432 in exactly the same manner asgiven for transverse cuts 453 and longitudinal cut 461 in paper ply 411of front top llap 431. In addition, parallel transverse cuts 46S areprovided in paperboard ply 413 of glue flap 425 and extend fromlongitudinal slit or cut 469, which is also provided in paperboard ply413 of side seam glue ap 425, being located in spaced relation to thelongitudinal edge of llap 425 and extending throughout substantially itsentire length. Transverse cuts 463 terminate in their parallel terminiequally distant from and located in spaced relation to score line 439.Exactly the same type of cuts or slits 463 and 459 are provided inextension 435. End flaps 433 and 434 and right hand end panel 423 arealso shown.

An exaggerated cross-sectional view of a carton erected from the cartonblank of FIGURES 12 and 13 and sealed by the application of heat or heatand pressure, taken along line XIV-XIV of FIGURE 4, is shown in FI"- URE14.

From FIGURE 14 may be seen front top flap 431 superimposed upon back topllap 432, which is in turn superimposed upon end iiaps 433 and 434.Thermoplastic laminant adhesive 412 has been extruded throughinterstices 466 in paper ply 411 of front top llap 431 and throughinterstices 462 in paperboard ply 413 of back top flap 432, therebyintegrally interbonding both front top flap 431 and back top llap 432and their respective upper ply 413 and lower ply 411 through interstices465' and 462. Adhesive 412 has also extruded from the cut edges of fronttop flap 431 and back top ap 432, thereby sealing said edges oft againstwicking. A portion of adhesive 412 has also extruded outwardly from thecut edges of aps 431 and 432, further bonding these two aps withpaperboard ply 413 of right hand end panel 423. Adhesive 412 has alsobeen extruded out of the cut edges of end aps 433 and 434, therebyforming a bond therebetween and also between them and lower or paper ply411 of back top tlap 432. Flap 425 and its extension 435 are alsoapparent, and the partially broken elevational View of the edge of saidflap shows adhesive 412 extruded through interstices 468 in paperboardply 413 of tlap 425, thereby forming an adhesive bond between Hap 425and inner or paper ply 411 of end panel 423. In the process of sealingap 425 to the inside of end panel 423 involving the application of heator heat and pressure, adhesive 412 has been extruded out of the cutedges of flap 425 and extension 435 throughout their entire lengths,sealing them against any possible wicking, as seen in FIGURE 14. In thisembodiment, interstices 46S and 469 may be absent from flap 425 andcorresponding interstices provided in the inner or paper ply 411 of endpanel 423 immediately adjacent its edge along which it is adhered to ap425, or the interstices may be present in both tlap 425 and panel 423.Similarly, interstices 468 and 469 may be absent from extension 435 butpresent in the inner or paper ply 411 of top llap 433 immediatelyadjacent its edge along which it is adhered 18 to extension 435, or theinterstices may be present in both extension 435 and Hap 433.

FIGURE 15 shows a partial plan view of a carton blank 520 formed fromlaminated sheet material 510 with thicker or paperboard ply 513 facingthe viewer. The panels, aps, and extensions of this carton blank aredefined by longitudinal score lines in spaced relation to the edge ofsaid blank, and by the parallel transverse score lines. Thus, front facepanel 521 is joined with glue ilap 525 and with left hand end panel 524along score lines 536 and 537 respectively, while back face panel 522 isjoined with left hand end panel 524 and right hand end panel 523 alongscore lines 538 and 539, respectively. Front face panel 521 is joinedwith its front top llap 531 along longitudinal score line 545, back facepanel 522 is joined with itsrback top ap 532 along longitudinal scoreline 546, end panels 523 and 524 are respectively joined to their endaps 533 and 534 along longitudinal score lines 547 and 548, and glueiiap 525 is joined to its extension 535 along longitudinal score line549, said longitudinal score lines all being extensions of each other.Usual transverse cuts extend from the edge of blank 520 to thelongitudinal score line between top ilap 531 and extension 535 and lefttop ap 534, and between back top llap 532 and right hand and left handend flaps 533 and 534. Transverse cuts 560 are also provided inpaperboard ply 513 of back top flap 532, as is longitudinal slit 561located in spaced relation to the longitudinal edge of flap 532. Cuts570 are provided in paperboard ply 513 of each of end aps 533 and 534,as well as slits 571 in spaced relation to the lateral edges of tlaps533 and 534. Cuts 560 are all parallel to each other and extend fromtheir origins equally spaced from slit 561 to their parallel termini,all equidistant from and in spaced relation to score line 545, whilecuts 570 are parallel and extend between slits 5'71.

Although in FIGURE l5 the transverse and longitudinal cuts are shown inpaperboard ply 513 of back top liap 532, these cuts could be absent fromback top flap 532 and present in thinner or paper ply 511 (not shown) offront top tlap 531. Moreover, back top flap 532 may be and preferably iscut aWay or recessed at its lateral edges.

FIGURE 16 shows an exaggerated cross-sectional view on line XVI- XVI ofFIGURE 4 of a carton erected from the carton blank of FIGURE 15 andsealed by the application of heat or heat and pressure.

As viewed in FIGURE 16, front top ap 531, back top ap 532, and end flaps533 and 534 are apparent, 531 overlying 532 which in turn overlies bothend llaps 533 and 534. End panel 523 of which lap 533 is an extension isalso shown. Thermoplastic laminant adhesive 512 has been extrudedthrough interstices 559 in paperboard ply 513 of back top tlap 532 toform a bond between back top lap 532 and the lower or paper ply 511 offront top flap 531. Likewise, adhesive 51.2 has extruded throughinterstices 573 in paperboard ply 513 of end tlaps 533 and 534, forminga bond at the upper surface of said end tlaps with the lower surface ofback top flap 532. Adhesive 512 has also extruded outwardly from fronttop flapV 531 and underlying back top ap 532, forming a protective layerover the cut edges of the various plies or" these liaps to preventwicking, and also bonding these aps to outer or paperboard ply 513 ofend panel 523. Adhesive 512 has also extruded outwardly from the cutedges of end flaps 533 and 534, bonding these aps together interiorly ofthe carton and also bonding the cut ends of these aps to the lowersurface of back top ilap 532.

FIGURE 17 is a partial plan View of one side of another carton blank 626embodying the invention, while FIGURE 18 is a partial plan View of thereverse side of the same carton blank. In FIGURE 17 thinner or paper ply511 of sheet material 610 faces the viewer,

19 while in FIGURE 18 thicker or paperboard ply 613 faces the viewer.The various parts of carton blank 620 as shown in'FIGURE 17 Correspondwith those shown for carton blank in FIGURE 3; the various parts ofcarton blank 620 shown in FIGURE 18 correspond with those shown forcarton blank 2? in FIGURE 2, with the exception of the heat-sealingareas. Back top flap 632 is again shown as recessed or cut away at itsedges 652 and 653, so as to provide a width at its longitudinal edgewhich is less than the width of its adjoining back face panel 622throughout most of its lateral reach, but is angled as at 654 so as toprovide a width at score line 646 which is the same as that of back facepanel 622. As shown in FIGURE 17,front top flap 631 is provided withcuts 672 in paper ply 611, diagonally disposed in spaced relation to thelateral and longitudinal edges of fronttop flap 631, which slits or cutspenetrate only the inner or paper ply 611 of sheet material 610.Likewise, as shown in FIGURE 18, similar diagonally disposed cuts 673vin paperboard ply 613 of back top ap 632 are also provided and aresimilarly located in spaced relation to the longitudinal and lateraledges of back top ap 632. End panel 623, end aps 633 and 634, and glueap 625 and its extension 635 are also apparent in FIGURES 17 and 18.

FIGURE 19 shows an exaggerated partial cross-sectional view onlinevXIX-XIX of FIGURE 4 ofa carton erected from the carton blank ofFIGURES 17 and 18 and sealed by the application of heat or heat andpressure. As viewed in FIGURE 19 at the intersections of the diagonalcuts 672 and 673, front top ap 631, back top ap 632, and end flaps 633and 634 are visible, flap 631 overlying liap 632 which in turn overliesboth end flaps 633 and 634. End panel 623 of which ap 633 is anextension, and glue flap 62S and its extension 635 are also shown.Thermoplastic laminant adhesive 612 has extruded through interstices 672in paper ply 611 of front top flap 631 and through interstices 673 inpaperboard ply 613 of back top ap 632, thereby integrally bonding fronttop flap 631 and back top ilap 632 together. Since this cross-sectionalview is taken at an intersection of the reverse diagonal cuts 672 and673 of front top ap 631 and back top flap 632, interstices 672 and 673are shown in alignment, it being understood that they will be out ofalignment except in a view taken at an intersection of the diagonal cuts672 and 673. Adhesive 612 has also extruded outwardly from the edge offront top flap 631 and back top flap 632, especially at lateral edge652, thereby sealing off said edge and forming an area of adhesive 612directly between bottom ply 611 and top ply 613 of front top ap 631 andtop ply 613 of end flap 633 in the area of overhang of back top flap632. by front top flap 631, and also sealing the cut edge of front topflap 631 against wicking. Interior of the carton, adhesive 612 hasextruded from the facing edges of end aps 633 and 634,. bonding themtogether and to the lower ply 611 of back top flap 632. Adhesive 612also extrudes outwardly from the cut edge of extension 635 of glue flap625, further sealing this edge against wicking, when heat or heat andpressure applied in sealing are of suticient magnitude. Thus, allexposed edges of the sealed carton shown in FIGURE 19 are sealed byadhesive 612 against wicking at their edges and all aps are securelysealed to each other.

FIGURES 20 and 21 are partial plan views of carton blanks designated 720and 320 showing inside or paper plies 711 and 811 of laminated sheetmaterials 711i and S10, from which the blanks are respectivelyconstructed, facing the viewer. The carton blanks 721B and S20 have allof the various parts shown in FIGURE 8, but heat sealing flaps 732 and332 in the carton blanks of FIG- URES 2O and 2l, and the heat sealingareas therein, are of a different design than those shown in FIGURE 8,although both involve perforations.

In FIGURE 20, backtop ilap-732 is provided with punched or dziiled holes774 extending through both of its outer plies, that is from ply 711through adhesive 712 and paperboard ply 713 (neither of which latter twoplies are shown). vThese drilled or punched holes 774 through back topflap 732 operate in the same way as the perforations 266 in the cartonblank of FIGURE 8 upon application of heat or heat and pressuretoprovide an etective sealing of the carton in the same manner as thecarton blank of FIGURE 8 is sealed (see FIGURE 9), except that front topflap 731 will not'bond directly to end ilaps 733 and 734 at its lateraledges since back top :Bap 732 has no recessed edge and will liethereinbetween.

In FIGURE .21, back top iiap 832 is provided with .two double convexelliptical cutouts 875 in spaced relation to its lateral edges whichprovide a means through which, upon erecting of the carton, closing andsealing the same, as by the application of heat or heat and pressure,the lower face of front top flap S31 is sealed directly by thermoplasticadhesive laminant 812 (not shown) extruding out of the edges of cutouts875 to the upper surface of end flaps 333V and 834, substantially in themanner indicated by FIGURE 9 for the carton blank of FIGURE 8, exceptthat front top flap 331 will not bond directly to end flaps 833 and 834at its lateral edges since back top iiap 832 has no recessed edge andwill lie thereinf between.

Cutouts 375 in back top flap 832 need not be elliptical, nor doubleconvex, but may take any desired shape or form or number of at leastone,L or two as shown in FIGURE 2l, or more, as shown for the circularpunchouts 774 in back top flap 732 of FIGUREZO, or many more as shownfor the perforations 266 in back top tlap 232 of FIGURE 8.

FIGURE 22 shows another carton blank embodying the invention, in whichface and end panels Iand glue flaps 921 through 925 are all partiallyvisible. Front top ap 931 has dimensions corresponding substantially toan end cross section of the carton to be erected from the blank, whileback top iiap 932 is cut away at its outer and lateral edges. Right handend ap 934 is provided with hook (or male lock member) 976 adapted to beinserted in eye (or female lock member) 977 of rectangular left hand endflap 933. Carton blank 921i of FIGURE 22 is formed from laminated sheetmaterial 910 with thinner or paper ply 911 facing the viewer, and slits96@ and 962 respectively in end fiaps 933 and 934 are provided only inthinner or paper ply 911. Slits 961) and 962 in thinner or paper ply 911of end aps 933 and 934, respectively, are located adjacent the scorelinealong which these end flaps adjoin their respective end panels. Uponerecting a carton from this carton blank and folding end iiaps 931, 932,933, and 934 in that order, with insertion of hook 976 into eye 977, andsubsequent application of heat and/ or heat and presysure to the end ofthe carton at its side edges, a sealed carton, adequately 'sealed alongtwo edges but closed centrally by means of the hook 976 Yand eye 977 andthus adapted for reclosure by means of the same, is provided.

FIGURE 23 shows a carton blank 1G26 formed of laminated sheet material161) having thinner or paper ply 1011 facing the viewer. Face and endpanels and glue flap 1621 through 1625' are visible. Similarly, fronttop flap 1631, recessed back top flap 1632, and end laps 1033 and 11134are apparent. Right hand kend flap 11334 is again provided with hook1676 adapted to be inserted in eye 1677 of end ap 1033. Back top flap1632 is pro vided with a series of circular; punch-outs 11174 in spacedrelation to its edges. Upon erecting, closing, and sealing of the cartonin exactly the manner givenfor the carton blank of FIGURE 22, anadequately tacked carton adapted for reclosure by means of hook 1676 andeye 1077 is provided.

FIGURE 24 shows cartonV blank 1126 formed front laminated sheet material1111i with thinner or paper ply 1111 facing the viewer, Face and endpanels and glue flap 1121 through 1125 are apparent. Front top Hap 1131,back top flap 1132, and end aps 1133 and 1134 are also shown. End flap113/3 is provided with hook 1176 and end flap 1133 is provided with eye1177. Back top flap 1132 is again partially cut away at its outer andlateral edges. The end ilaps 1133 and 1134 and back top ilap 1132 arerespectively provided with slits 11611, 1152 andk 1178, these slitsbeing in thinner or paper ply 1111 and in end flaps 1133 and 1134 beinglocated adjacent the score lines along which these end flaps adjointheir respective end panels. Upon erecting the carton, folding theflaps, and sealing as given for the carton blank of FIGURE 22, a moreadequately sealed carton but again adapted for reclosure by means of thehook 1176 and eye 1177 is provided. The cuts may also be in the outer orupper ply of flap 1131 instead of or in addition to those in the innerply of flap 1132.

FIGURE 25 shows carton blank 122@ of laminated y sheet material 12113with thinner or paper ply 1211 facing the viewer. Face and end panelsand glue naps 122 through 1225 are all apparent. Back top ilap 1232 andend flaps 1233 and 1234 are of conventional type and are all ofapproximately equivalent lateral reach and have rounded corners. Fronttop flap 1231 is of somewhat greater lateral reach than the other flaps,is generally of the dimensions of an end cross-section of the carton tobe erected, and is provided With a series of longitudinally arrangedvertical cuts 12611 in its thinner or paper ply 1211 near itslongitudinal edge. Upon erecting the carton, folding end liaps 1233 and1234 in, back top flap 1232 in upon the two end naps, and front top flap1231 upon the back top riap, and then applying heat or heat and pressurein the vicinity of the cuts 126i) but at the outer exposed surface offront top flap 12.11, an adequately tacked and tamper-proof carton isprovided. In this embodiment, the cuts may he in back top flap 1232adjacent the score line along which it joins its face panel 1222 inaddition to or instead of the slits in flap 1231. The isometric view ofFlGURE 26 shows a carton blank 1320 of laminated sheet material 131@with thicker or paperboard ply 1313 forming the exterior of an end orfront opening trunk-style carton erected therefrom and with thinner orpaper ply 1311 disposed interiorly of the carton. In' this view, theheat-sealing areas are shown exposed to View. The carton blank fromwhich the carton of FGURE 26 is erected comprises a bottom face panel1321, top face panel 1322, front panel 1323 and back face panel 1324,End ilap 1333 is attached to front face panel 1323, end flap 13.34 isattached to back face panel 1324;, inner end flap 1331 is attached tobottom face panel 1321, and rounded end flap 1332 is attached to topface panel 1322, all along the longitudinal score line of the startingcarton blank 13211. A series of cuts 1360 is provided in the inner orpaper ply 1311 of end ilap 1334. Likewise, a series of cuts 1363 and 13@are provided in the thinner or paper ply 1311 of flap 1325, which isarticulated to top face panel 1322. As viewed with flap 1325 upright,slits 1361i are vertical and slit 1369 is horizontal or longitudinal offlap 1325. ln erecting the carton of FIGURE 26, upon folding inner sidetlap 1331 into a vertical position with respect to its adjoining bottomface panel 1321, folding rounded end iap 1332 into a vertical positionwith respect to its adjoining top face panel 1322, folding end flap 1333-upon inside end tlap 1331 and end flap 1334 upon end flap 1333, andthen inserting the rounded end Ilap 1332 into the pocket formed by endfiaps 1331, 1333 and 1334, which latter two ilaps constitute the cuterend of the carton, an end or front opening trunk-style carton having thestructure shown in FIGURE 26 is provided. Upon the application of heator heat and pressure to the vertical edge of end flap 134, an eihcientseal between end flap 1334 and end ilap 1333 is provided in the area ofcuts 1361i. Likewise, upon the folding of iiap 1325 downwardly upon theouter surface of front face panel 1323 and the application of heat orheat and pressure to the outer surface 1313 of the said ilap 1325, aneffective seal is provided between ilap 1325 and front face panel 1323in the area of cuts 1368 and 136i?. Upon openingT of the carton by therupture of the seal in the area of cuts 1363 and 1369 of flap 1325,access to the contents i-s provided, but the carton is effectivelyreclosable due to the frictional Contact maintained by rounded end ilap1332 in the pocket provided by inner end flap 1331 and the outer endflaps 1333 and 1334. ln this embodiment, slits may be present in outerply 1313 of end ap 1333 along its vertical edge in addition to orinstead of those in flap 1334, and may be present in outer ply 1313 offront face panel 1323 in addition to or instead of those in front flap1325.

It will be noted that FIGURES 21 through 26 relate to tackortamper-proof type sealing carton blanks and cartons, as opposed tohermetically or leak-proof sealing type of carton.

It will also be noted that FIGURES 8, 9, 10, 11, 20, 21 and 23 relatedto carton blanks and cartons of laminated sheet material havingperforations, punch-outs, or cutouts in a flap adapted to be anunderlying iiap upon erection of the carton and folding `of the ilapsupon each other to provide a closure of the carton. It is more-over tobe noted that a recessed, relieved, or cut-away underlying flap may beprovided as indicated in FIGURES 8 through 11 and 23, especially 8 and9.

It is further desired to point yout that FIGURES 2, 3, 5, 6, 7, 12, 13,14, 15, 16, 17, 18, 19, 22, 24, 25 and 26 show carton blanks and cartonshaving slits or cuts disposed in one ply only of one or more closureilaps.

It is moreover desired to point out that FIGURES 13 and 14 show slits,through a single ply of the laminated sheet material of a carton blankand carton, disposed on the flap employed for closing of the side seamof the carton, previously ordinarily referred to in the art as the gl-uellap.

It is also desired to point out that FIGURE 26 shows a carton having aside seam sealed by cuts, in la single ply of the laminated sheetmaterial at an area of overlap of two side or end wall flaps, which uponapplication of heat `or heat and pressure provides an adequate sealbetween the two side or end flaps in the area of overlap provided withsaid slits or cuts into the layer of thermoplastic laminant.

It is moreover desired to point out that FIGURE 26 also shows a fronttop closure Hap attached to a hingedcover carton provided on its innersurface with slits `or cuts through the outer ply and into the layer lofthermoplastic adhesive larninant for bonding the front topy closure flapto the outer surface of the front face panel upon the application ofheat or heat and pressure tothe exterior surface of said front closureap.

It is also desired to point out that the cart-on blanks and cartons ofFIGURES 2, 3, 5, 6, 7, 17, 18, 19 and 24 are provided with a ilap, whichis designed to be the intermediate ap upon closure of the carton, havingrecessed, relieved, or cut-away edges, which said relieved edgescooperate with the slits `or cuts in the upper ply of the inner flap orthe inner ply of the outer flap, or both, to provide an unprecedentedseal of said carton, especially inthe area of overhang of said recessedflap by said top ilap, or with perforations, cut-outs, yor punch-outs insaid relieved flap to provide an unprecedented bonding of the innerflaps directly to said cuter ap due to rivets of adhesive wherever suchperforations or the like are provided. Itis apparent that in someembodiments the slits or cuts shown in the innerkply of the outer flapor the outer ply of the inner ilap, or both, will preferably not bepresent in the area of :overhang of the relieved intermediate iiap bysaid outer flap, but only in the area in which surfaces of theintermediate and outer flaps are opposed.

It is moreover pointed out that FIGURES 2, 3 and 5 illustrate cartonblanks and cartons having slits in the plies which will be the inner plyof the outer ilap and the inner ply of an intermediate flap upon closingthe carton; that FIGURES 6 and 7 illustrate carton blanks and cartonshaving slits in the ply which will be the inner ply of the outer iiapupon closing of the carton and which can equally well be located in theupper ply of the intermediate iiap upon closure of the carton; thatFIGURES 12, 13 and 14 illustrate carton blanks and cartons having slitsor cuts in the inner ply of the outer ap and the upper ply of theintermediate flap upon closure of the carton; that FIGURES 15 and 16illustrate carton blanks and cartons having slits or cuts in the upperply of the inner flaps and in the upper ply of the intermediate flapupon closure of the carton, which combination can also include slits orcuts in the inner ply of the outer ap upon carton closure, or which canequally well be replaced by slits or cuts in the upper ply of the inneraps and in the inner ply of the outer flap upon closure of the carton;that FIGURES 17, 18 and 19 illustrate carton blanks and cartons havingslits or, cuts in the upper ply of the intermediate flap and .in theinner ply of the outer ap upon closure of the carton; that FIGURE 22illustrates carton blanks and cartons having slits or cuts in the outerhook and eye end flaps adjacent the score line along which they arejoined to their respective face panels; FIGURE 24 shows the same thingexcept that, in addition to the slits or cuts provided in the outer-maleand female lock flaps, slits or cuts also provided in the inner ply ofthe intermediate flap and could also equally well be provid-ed insteadin the upper ply of the inner flap or in both the upper ply of the innerflap and the lower ply of the intermediate iiap; and that in FIGURE 25slits or cuts are provided in the inner ply of the outer Hap in the areaadjacent its longitudinal edge.

In operation, a carton blank is produced from suitable laminated stock,such as the laminated sheet material shown in FIGURE 1,the blank havingaconfiguration the same as or similar to those shown in the drawings. Theselected base sheets or plies are rst laminated together with sufficientthermoplastic adhesive laminant according to conventional procedure, aswith metering rods, squeeze-roll laminators, and reverse rolllaminators, and the requisite ply openings provided-in the heat-sealingareas of the carton blank at any one or more ofseveral stages of itsconstruction from the selected laminated sheet materials. The exactorderv of steps whereby the blank is constructed is of minorsignificance, except that the desired openings oe provided after thelamination as indicated previously. The selected base sheets may belaminated with the requisite quantity of selected thermoplastic adhesivelaminant, the laminated sheets printed as desired or otherwise providedwith any necessary artwork, thev requisite openings Vin thealready-determined heat-sealing areas preferably provided at this stage,and the sheet then scored and die cut in one or4 several separateoperations to the desired dimensions. Scoring, die cutting, andprovision of the openings may also be done simultaneously.Alternatively, the order may be: lamination, printing, scoring and diecutting, and provision of requisite openings in the heat-sealing areas;or, printing of the base sheet materials, lamination, provision of theopenings in the heat-sealing areas, and scoring and die cutting. Theorder may also be: printing of the base sheet materials, lamination,scoring and die'cutting, and provision of the openings in theheat-sealing areas. At any rate, the openings of the heat-sealing areaswill in all cases be indexed, aligned, `or oriented with respectto'flaps or other carton members having need to be sealed or secured andmay also be koriented with respect-to the desired printing or artwork,and will be located in one or more plies of the carton members which areto be heatsealed. Any driving force as further mentioned herein willordinarily be provided at some point, such as during rotogravure orother printing of the sheet materials, but at any rate at some stageduring the carton blank formation stage if not already coated upon or ina base sheet material. The quantity, type, and disposition of theopenings in the heat sealing areas, as well as the heat-sealing areasthemselves, willvary depending upon the application of the carton andthe intended manner of employing the heat-sealing closure thereof. For atacked lor tamperproof closure, the heat-sealing area will ordinarily beof -smaller area than when a hermetic seal .is desired, eg., involving`a series of interstices along one ap edge rather than generally or evensubstantially throughout an entire ilap area, and will ordinarilyinvolve only one or a few closure aps rather than most Kor all of themwhich are usually involved in providing a hermetically sealed cartonclosure. The heat-sealing areas and the openings provided in the pliesof the carton closure members in these heat-sealing areas will be asmore fully illustrated by the drawings and as described elsewhere inthis specification. When a front flap or a side-seam closure flap or asideseam overlap closure ap, or the like, are involved, the openings maybe provided either in they ply of the flap itself or in the ply of theflap or carton face to which it will be adhesively secured, or both,Vjust as in providing heat sealing areas in the more usual carton endclosures the openings may be either in one or both of the opposed pliesof the laminated sheet material constituting the ap surfaces.

After provision of the carton blank with suitably disposed heat-sealingareas, a carton body is erected from the formed carton blank by seamingin the usual manner by securing two face panels thereof by means of asidesealing ap, as by folding the carton blank along one score lineabout one hundred eighty degrees so as to place the side-sealing ap in ahorizontal position facing upwardly, folding the carton blank alonganother score line so as to bring the inside of the face panel which isto be adhered to the side-sealing iiap into overlying relation withrespect to said side-sealing flap, and'then securing the flap and panelto each other, a folded carton body or tube being thus produced. Glue orother adhesive is conventionally used for securing such members and isusually satisfactory. Application of adhesiveactivating conditions tothe glued or otherwise secured side seam either at this point or justprior to adhering the flap to the panel, which usually involvesapplication lof a certain amount of pressure, extrudes thermoplasticadhesive from the cut edge of the side-sealing ilap, which upon settingof the adhesive is thus sealed against wicking. Since, according to theinvention, either or both of the upper surface of the side-sealing flapand the inner surface of the panel in the area to be adhered to saidflap vis provided with openings into the layer of intercalatedthermoplastic adhesive laminant in theirV area of overlap (see FIGURES13 and 14), the seam-ing may be effected in the manner given withapplication of heat or heat and pressure to this heat-sealing area,which frequently extends substantially the full lengthof the side seamof the carton, resulting in extrusion of the thermoplastic laminantadhesive through the said openings and the cut edges Iand provision ofan effective seal between the inside of the face panel and the outersurface of the side-seam `sealing flap in the said area lof theiroverlap or juxtaposition.

The same method of operation, but after carton erection, is employedwhen a front flap is to be adhered to a front face panel, such as in thecarton shown in FIGURE 26, except that in such case the heat-sealingareas and openings into the intercalated thermoplastic adhesive layerare provided in the outer surface of the front face panel or in theinner surface of the front flap, or both, and the application of heat orheat and pressure or other adhesive- VactivatingV conditions in the areaof overlap of the said flap and face panel produces an effective sealtherebetween due to extrusion of thermoplastic adhesive larninant fromthe intercalated laminant layer through the openings provided in said apand/ or panel ply.

After seaming the carton by securing two face panels by means of theside-sealing flap, Whether the conventionh al glue type or having a heatsealing area according to the invention, the folded carton may beshipped fiat and/or unfolded ninety degrees t-o form a tube. The cartonmay then be closed by folding in the inner flap or flaps, folding theintermediate ap upon the inner fiap or aps, and folding the top or outerflap upon the intermediate fiap, all of said flaps usually beingarticulated to carton face panels. Filling of the carton is usuallyeffected after closure of one end thereof, but may be effected afterboth ends of the carton are closed in the case of trunkstyle orfront-opening carton constructions (see FIGURE 26). The application ofheat or heat and pressure to the heat sealing areas after carton closureproduces an effective seal due to extrusion of the thermoplasticadhesive laminant from the openings in the plies of the various aps orother heat sealing areas of the carton construction and by extrusionfrom cut edges. The glue ap at the side seam, if not previously heated,can be heated lfor edge-sealing purposes after carton erection orclosure and even after filling of the carton, just as well as at anearlier stage.

Adhesive-activating conditions may also be provided in selected cases byinfra-red rays, dielectric heating, or application of electronic meanssuch as microwaves, and in some cases, as already indicated for the glueiiap, especially where pressure will be employed in sealing, theadhesive-activating conditions may be applied momentarily just beforeclosing all or even any of the closure aps rather than after. It isapparent that the adhesiveactivating conditions must be applied in theVicinity of the heat-sealing area desired to be heat-sealed and to theflap or other carton member provided with the openings through which thethermoplastic laminant adhesive is desired to extrude, and that theseadhesive-activating conditions will preferably be applied to theexterior of the carton after closing, usually most conveniently to theouter flap of the closed carton, or in any event to the exterior of thecarton adjacent the area in which the heat seal-ing is desired to beeffected. The application of adhesive-activating conditions is followedby adhesive setting conditions, which will ordinarily involve cooling orotherwise allowing the thermoplastic adhesive larninant to congeal,preferably under pressure contact, to prevent the flaps from springingapart until the adhesive has set or solidified, or has at leastconsiderably increased in tack or viscosity. Upon setting of theadhesive, an effective seal is provided in the particular heat-sealingarea in question in the manner fully indicated by the drawings,involving a seal of the one carton member to the other in the area oftheir opposed facing relationship by means of bodies of solidifiedthermoplastic laminant adhesive extending from the intercalated laminantlayer of at least the one carton member through the -openings providedin the ply of that member to at least the surface of the other cartonmember.

When the intermediate iiap of the carton closure is recessed along anedge thereof so as to be narrower, usually in breadth, than the louterflap along at least a portion of an edge thereof, and so as to providean area of overhang of said intermediate flap by said outer flap whensaid flaps are folded upon each other in closing of the carton, at leastone and usually at least two inner flaps will provide a surface foropposed facing relation with said outer flap at a point where saidintermediate flap is narrower than said outer flap. The outer flap willusually but not necessarily be dimensioned generally to cover the entireend cross-section of the carton body, and the intermediate fiap willalso usually but not necessarily be dimensioned generally to cover theentire end cross section of the carton body, but in any event will haveedge portions where the same would ordinarily be exposed in the closedcarton slightly recessed :so as to extend inwardly of the correspondingedges of the outer iiap. One or more recesses or areas of overhang insaid closure will thus be formed and adapted to be filled with adhesive,`and the application of adhesive-activating conditions to the saidintermediate flap will cause the thermoplastic adhesive laminant carried-between the plies of the intermediate flap to extrude outwardly of therecessed edge thereof to late/r congeal and thereby effect a sealbetween the surface of the outer flap and the surface of the inner flap,in said areas of overhang, by means of said extruded thermoplasticadhesive laminant, thereby also sealing off the cut edge of the saidintermediate flap without however disposing any or substantially any ofthe thermoplastic laminant adhesive upon the exterior exposed faces ofthe carton.

A basic seal or taclt between the surfaces of the carton aps or othermembers, such as between the intermediate flap whether recessed or not4and the outer flap, where convenient, may in some cases be effected bythe employment of conventional glue or other adhesive, leaving thesealing between the outer flap and the intermediate ap, the inner ap orflaps and the intermediate iiap, and between the outer flap and theinner liap or flaps in the area of overhang where such exists to beeffected by the application of heat or heat and pressure or otheradhesive-activating conditions. Thus, in one manner of operation, oneend of the carton may be tacked with glue or other adhesive ofconventional nature, the carton may be Ifilled, the other end of thecarton closed, and the ends of the carton sealed by the application ofheat or heat and pressure or other adhesive-activating conditionsthereto, either individually but preferably at both ends simultaneously,and the thermoplastic laminant adhesive thereby extruded throughinterstices and cut edges allowed to congeal. l he same procedure oftacking with glue or other adhesive and thereafter extrudingthermoplastic adhesive laininant through ply interstices and/or cutedges to form the seal may be applied to side-seam sealing iiaps, fronttop flaps, side-seam overlaps, and the like, with or without filling ofthe carton after tacking but before sealing by extrusion and setting.

When sealing a carton provided with a recessed intermediate flap, thethickness of the sealing adhesive provided in situ in the recess betweenthe outer iiap and the inner or flaps, by extrusion from the recessededge of the intermediate flap in combination with any openings from theouter hap or inner iiap or tiaps into the area of overhang, providesincreased strength and resistance to handling, scufng, andmoisture-vapor transfer, and this thickness of adhesive in the saidrecess ordinariiy fills the entire space separating the outer liap fromthe inner fiap or aps and is usually of a thickness approximatelyequivalent to that of the intermediate Flap. Upon sealing by `extrusionof thermoplastic adhesive from the recessed edges of an intermediateflap, especially when heat and pressure are employed, the thickness Iofthe intermediate flap is frequently somewhat reduced and the extrudedadhesive in the recessed area thus readily attains a thicknessapproximating that of the somewhat flattened intermediate flap. Inaddition, the inner fiap may be and in some cases preferably is somewhatshortened so as to correspond upon folding with the contour of therecessed edge of the intermediate fiap, or substantially so, or it mayeven be embossed or suitably contoured so as to provide Va recess orseat for the relieved edge of the intermediate ap where said inner flapunderlies the said intermediate flap, whereby the opposed surfaces `ofthe inner and outer fla-ps are brought closer together.

While in the drawings it is indicated that thermoplastic laminantadhesive also extrudes out of the cut edges of the innermost flaps ofthe carton construction and While such does ordinarily occur whensealing the care, legga-74- 2.7 tons against a mandrel lor underconsiderable heat and/ or pressure, it is to be understood thatextrusion of the adhesive from the cut edges of the innermost ilaps,while preferable in some instances, is optional and not a requisite forsatisfactory sealing of the cartons. Moreover, `/vhere the drawings showcarton blanks having a recessed intermediate iiap attached to the backface panel of the carton, the recessed intermediate flap can equallywell be attached to the front face panel of the cart-on and the outerflap, usually having dimensions generally approximating those of thecarton end cross section, can equally well be attached to the back facepanel. Further, the recessed inter-mediate ap at one end of the cartonmay be attached to the front face .panel while at the other end of thecarton the recessed intermediate flap may be attached to the back facepanel, and vice versa. in addition, the relieving, recessing, or cuttingback of the edges of the intermediate ilap is not restricted to anyparticular geometric design or form of the intermediate flap or recess,and in one embodiment, for example, the

intermediate flap may simply be tapered from its juncture withV itsadjoining face panel to a somewhat reduced width at its outer edge.

The following examples are given to illustrate some of the advantages ofmy method of forming carton blanks and heat-sealing cartons, as well asadvantages of the carton blanks and cartons themselves, but are not tobe construed as limiting.

Example 1 `Clay-coated Fourdrinier paperboard .012 inch thick(guaranteed minimum 1500+ seconds porosity) was laminated to a iiftypound dry waxed sulte sheet .0035 inch thick (14 seconds porosity) using.006 inch of laminating adhesive consisting of 3.6 percent butyl rubberand 96.4 percent microcrystalline wax of Mid-Continent origin melting at15S-165 F. (Bareco-Ceratak). The laminated sheet was scored and die cutby ordinary means on a job press, with the .012 inch coated board on theoutside, coated side out. Slits were then cut in the inner ply deepenough to penetrate the inner ply (dry waxed sheet) but insufficient indepth to completely penetrate the laminating adhesive. The blank wassubstantially as shown in FIGURES 2 and 3. The side seam of the cartonblank was glued with a polyvinyl acetate a-dhesive according to standardIpractice and a carton erected therefrom. Y

Folding cartons thus formed were placed over a mandrel the size of theinside of the carton, and the bottoms 2S; The cartons were then frozenfor ve days and thawed for one day, and were still found to beleakproof.

In a like manner, the above-describedv cartons were heatedat their sideseams to extrude laminant to the in- Vside ofthe carton,-their bottomtlaps closed, the carton iilled, top flaps closed, and the cartons heatsealed. The cartons were tested when iilled with brown sugar,hygroscopic gelatin dessert powder, cake ilour, powdered milk, frozenstrawberries in syrup, and sugared cereal. After ve months ofstorage,alternately between 90 percent relative humidity `at 100 F. and50 percent relative humidity at 73 F., these foodstus were in goodcondition. The frozen strawberries were stored at -10 F.

Example 2 A clay-pigment coated 59 pound per ream book paper .0035 inchthick (3000+ seconds porosity) was laminated to a fty pound per ream drywaxed paper .0035 inch thick (14 seconds porosity) witlrwax laminantcomposed of 85 percent microcrystalline wax (Bareco-Ceratak), 1.66%hydrogenated tallow amides containing 22% hexadecanamide, 75%octadecanamide, and,3% octadecenamide (Armid HT) and 13.33 percentpowdered attapulgite having a particle size between about two and about.02 microns with an average particle size of about .14 micron,containing seventeen percentrmoisture (Attagel 20). The laminatingcomposition was applied in thicknessesof .0013.0023, .003, -004,'.0046and .007 inch. Carton blanks of the design shown in FIGURES 2 and 3 werecut from the laminated stocks, glued with `moistureproof adhesive,cartons erected therefrom, and tested for heat scalability andleakproofness to water.l Cartons from stocks having less than .004 inchof Wax in the laminant layer failed to heat vseal properly, while thosewithgreater than this amount of wax sealed well and were leakproof whentestedwith water. The `laminant used in this experiment had a density ofiifteen ream pounds (24 x 36 x 500) per .001 inch thickness.

Example 3 A number of brous sheet materials were combined with severallaminating agents, specimens the size of carton flaps were cut from thelaminated sheets, then the inside sheets were slitover an area of onesquare inch using` parallel slits, providinginterstices extending intothe laminant ply, and the thus-treated sheets tested forheat-scalability in a face-to-back (thinner ply to thicker ply)relationship (as'shown in FIGURES 2, 3, 5, v6 and 7) with the followingresults:

Outside sheet Inside (slit) sheet Laminating agent and (thieimess)Hetl-.steala Am- 501s. dry waxed (m35/o1 5011;. dry waxed @0035/01{bgtrallbx 0O6) kroon.

13...- 59 lb. coated book (.0035)1 96.4% Ceratak Wax (.006") Excellent0.--. --.d0.1 23 1b. 'rior-enea surprise (m2/f) {gbgtnlgfafi--O@ no. n[13 seconds porosity1.l l i 3 6%"butyl rlbber D .012 clay-coatedpaperboard 1.-.-. lb. dry waxed (.0035 )1 {96.4%} Ceratak Wai-(bfn Do. E.014 solid news paperboard [300+ do.1 Attagel-Armid HT-Ceratak wax Do.

seconds porosity guaranteed Y composition (of Example 2) r minimum](.0065). I" .012 clay-coated paperboard.1 .do.1 Wax-silica(microcrystallino wax Good.

bodied with colloidal silica) (.0G).

1 Same as in previous examples.

It is clear that it is entirely unnecessarythat the inside i sheet be aporous sheet, or even more porous than the outside sheet, as evidencedby the following example.

' Example 4 A 27 pound pergream vegetable parchment paper (1500+ secondsporosity) was laminated to a .012 inch clay-coated paperboard (same asin Example 1)k with .007 inch of laminating agent composed of 1.5percent of hydrogenated tallow amides (Armid HT), 1.5 percent titaniumdioxide (TiOg), eighty-four percent Pennsylvania grade microcrystallinewax, Ml. G-160 Fahrenheit (Quaker State L500), and thirteen percent ofpowdered attapulgite (Attagel and mixed to a viscous thixotropic stateunder high shear. The laminated sheet was scored, die cut, and theparchment surface slit as shown in FIGURE 3. When heat sealed at theglue seam and both ends, the cartons erected from the thus-producedblanks were found suitable for the packaging of greasy foods such asprocess cheese, natural cheese, oleomargarine, butter, chop suey,cottage cheese, and shortening with no sign of leakage or staining afterthree months storage.

As noted in Example 4, it is sometimes advantageous to apply heat to theglue seams to provide an extrusion of laminating composition in thesezones. If it is desired to form heat sealed glue lines, slits may beprovided along the surfaces of the inside sheet where it will overlapthe outside sheet (see FIGURES 13 and 14), or in the outside sheet, orin both sheets. In other cases it is satisfactory to glue the carton inthe regular manner, then apply heat at the juxtaposition of the rawedges of the side seam to extrude adhesive over any exposed raw edges.With dry products in the package, it is frequently unnecessary to applyheat at overlapping glue lines, as at the carton side seam.

In addition to seals in a face-to-back relationship (as in FIGURES 2, 3,5, 6 and 7), I find that in some applications, such as in prescoredbacon sleeves, cheese packages, milk bottles, and the like, it isadvantageous to seal inside surfaces to inside surfaces. In this case,excellent seals are obtained whether one or both of the contiguoussurfaces are slit for extrusion of the adhesive.

In some applications it is not desirable to extrude adhesive at the cutedges, in which case the openings, eg., slits, may be at some distance,for example one quarter of an inch, away from such cut edges, and heatapplied only at these positions (see FIGURES 22-25) I have moreoverfound that it is possible to completely perforate portions of the sheetmaterial, especially those portions forming inner and intermediate flapsof a folding carton. In these cases it is possible to cause the adhesiveto flow to either or both sides of such flaps to form a satisfactorybond to contiguous flap or other surfaces. Top flap constructions ofsuch heat sealing carton blanks and cartons are shown in FIGURES 8, 9,10, 11, 20, 21 and 23.

Example 5 Carton blanks as shown in FIGURE 8 were cut from a stockcomposed of 59 pound coated book paper .0035 inch thick laminated to afty pound dry waxed sulphite .0035 inch thick with ninety pounds perream of a wax composition composed of thirteen percent attapulgitepowder (Attagel 20), 1.5% of hydrogenated tallow amides (Armid HT), 1.5%titanium dioxide (TiOz), and 84 percent laminating grademicrocrystalline wax. The flaps were perforated in the same operation inwhich the blanks were scored and cut on a platen press. When formed intocartons and heat sealed at 400 Fahrenheit for one second, these cartonsadequately protected powdered `skim milk, cereal, dehydrated potatoes,and hygroscopic dessert powder for extended periods under varyingclimatic conditions. v

The process of heat sealing cartons of the invention by extrusion ofadhesive from the interstices provided in one or more plies of cartonmembers with or without additional extrusion from recessed edges of anintermediate ap is not only advantageous because of its readyadaptability to both leakproof and non-leakproof seals, and the highquality of such seals, but is moreover particularly advantageous in thatfor most purposes it obviates the use of a mandrel for sealing. Thenumber of cartons which can thus be heat sealed in a given time isgreatly 3@ increased over that previously attainable in view of the factthat the maximum number of cartons which can be sealed per minute usinga mandrel is about ninety, while on present day packaging machineryWithout the necessity of employing a mandrel the number of cartons whichcan be sealed per minute is on the order of four hundred. In accord withthe foregoing disclosure, an especially suitable liquid-proof closurefor containers especially adaptable to the storage or transportation ofliquids is formed in the manner of the invention by providing the cartonbody with the usual two inner aps, an intermediate flap, and an outerflap, said outer flap having generally the dimensions of an endcross-section of the carton body, which cross-section is ordinarlyrectangular, e.g., square. The intermediate flap is usually cut-away orrecessed at its edges in the manner hereinbefore disclosed, so as to benarrower with respect to the outer flap, although usually of the samewidth as its adjoining face panel at its juncture therewith. The innerflaps are provided with openings in the ply thereof which is outwardlydisposed upon closing of the carton, and said outer ap has openings inthe ply thereof which will be inwardly disposed upon closing of thecarton. Openings in the ply of the inner flap which will be outwardlydisposed and/ or in the ply of the outer flap which will be inwardlydisposed upon closing of the carton are preferably provided in the areaof overhang of said intermediate ilap by said top ap when saidintermediate ap is recessed at its edges. The said intermediate flap isprovided with openings in both of the base plies thereof, and ispreferably pcrforated from surface to surface thereof without removal ofsheet material or by punching so as to remove a port-ion of the sheetmaterial of construction of said intermediate ilap within localizedareas. Cartons constructed in such manner, upon closing of the liaps andsealing, which is in such case usually effected against a mandrel, havebeen found to be extremely leakproof and liquid-proof, and for examplehave special application as milk cartons and the like. For such type andother liquid-proof cartons, as will be apparent from the previousdisclosure, a dry waxed sheet is preferred as the inner ply of thelaminated sheet material of the carton construction, and such adry-waxed sheet having a weight of about twenty to thirty, e.g., 27pounds, per ream prior to waxing is especially suitable. The out-sideply of such sheet material to give a carton especially suitable as aliquid-proof container will ordinarily be paperboard having a caliperranging from about .0l to about .018 inch. Especially suitable cartonsuseful because they need not be sealed against a mandrel are thosewherein openings are provided in the inner ply of the outer flap with orwithout additional openings in Vthe inner ply of the intermediate flap,and especially where such outer plies are pigment or clay-coated orcoated with a combination of such materials, in which case the drivingforce provided upon application of thermoplastic adhesive laminantactivating conditions to the carton exterior effectively drives theadhesive from the intercalated laminant layer of the outer flap, and ofthe inner flap when provided with openings in its inner ply, through theopenings provided in such flaps thereby to effect an efficient seal withunderlying flaps without the use of a mandrel, and the provision of suchcarton blanks and cartons having such open-ings in the inner ply of theouter liap with or without additional openings in the inner ply of theintermediate ap and with or without, but preferably with, recessing ofthe edges of the intermediate flap, therefore constitutes a preferredembodiment of the invention.

It is thus seen that the present invention provides novel carton blanksand cartons, and a novel method of forming such blanks and cartons,especially sealed cartons, whereby all of the objectives of theinvention are accomplished and whereby the packaging industry isprovided with a new approach to carton packaging, due to elimination ofmany of the problems and shortcomings which have

1. A SCORED CARTON BLANK OF LAMINATED SHEET MATERIAL HAVING AN OVERALLTHICKNESS OF AT LEAST .008 INCH SUITABLE FOR FABRICATION INTO A SEALEDCARTON, THE BASE PLIES OF WHICH LAMINATED SHEET MATERIAL COMPRISE ATLEAST TOW SHEETS WHICH ARE INDIVIDUALLY AT LEAST .002 INCH THICK ANDHAVE A POROSITY OF AT LEAST FIVE SECONDS, AND IN WHICH THE LAMINANT IS ATHERMOPLASTIC ADHESIVE LAMINANT PRESENT IN AN AMOUNT OF AT LEAST ABOUTFIFTY-FIVE POUNDS OF LAMINANT PER REAM OF LAMINATED SHEET MATERIAL, SAIDCARTON BLANK COMPRISING A PLURALITY OF CARTON MEMBERS, INCLUDING PANELSAND FLAPS ARTICULATED TO SAID PANELS ALONG SCORE LINES, AT LEAST SOME OFSAID CARTON MEMBERS BEING ADAPTED TO BE FOLDED UPON EACH OTHER TOPROVIDE A PLURAL LAYERED CLOSURE IN WHICH ONE CARTON MEMBER LIES INJUXTAPOSITION TO ANOTHER CARTON MEMBER SO AS TO PLACE A SURFACE OF THEONE CARTON MEMBER IN OPPOSED FACING RELATION TO THE SURFACE OF THE OTHERCARTON MEMBER AND THEREBY PROVIDE AN AREA IN WHICH A SEAL BETWEEN SAIDMEMBERS CAN BE EFFECTED, AT LEAST ONE OF SAID CARTON MEMBERS BEINGPROVIDED, IN A PLY THEREOF CONSTITUTING A SURFACE THEREOF WHICH WILLCOME INTO OPPOSED FACING RELATIONSHIP WITH THE SURFACE OF THE OTHERCARTON MEMBER IN THE SAID SEALING AREA UPON FOLDING OF THE CARTON BLANKIN ERECTING A CARTON THEREFROM AND CLOSING OF THE SAME,